Absorbent barrier structures having a high convective air flow rate and articles made therefrom

ABSTRACT

Absorbent articles which provide superior protection against wet through under impact or sustained pressure, and high convective air flow therethrough for skin health and comfort benefits. In particular, an absorbent article comprising an absorbent core and an absorbent barrier structure, wherein the absorbent barrier structure has a hydrohead value of at least about 10 mBars; a convective air permeability of at least about 10 Darcy/mm; and a liquid impact transmission value of less than about 20 g/m 2 .

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation-in-part of U.S. patentapplication Ser. No. 09/883,434, filed Jun. 18, 2001 now abandoned,which is a continuation-in-part of and claims priority under 35 U.S.C.§119 to PCT Application No. US 00/17084, filed Jun. 21, 2000.

FIELD OF INVENTION

The present invention relates to absorbent articles which providesuperior protection against wet through under impact or sustainedpressure, and high convective air flow therethrough for skin health andcomfort benefits. In particular, the present invention relates to anabsorbent barrier structure for such articles.

BACKGROUND OF THE INVENTION

Many known absorbent articles such as diapers, incontinence articles,feminine hygiene products, and training pants, typically compriseabsorbent core materials located between a liquid pervious body-sideliner or topsheet and a vapor permeable, liquid impermeable outer coveror backsheet. The bodyside liner allows bodily liquids to flow througheasily and towards the absorbent core. The absorbent core takes up theliquids quickly. Thus, no excessive pooling of liquids occurs on thebody-facing surface of the absorbent article. The outer cover istypically liquid impermeable such that there would be no leakage fromthe absorbent article. However, because the disposable absorbent articlemay be worn for hours, sometimes after the absorbent article has takenup liquids, perspiration from the wearer's body, and liquid vaporsescaped from the absorbent core, can get entrapped in the space betweenthe absorbent article and the wearer's skin, resulting in an increasedrelative humidity in the occluded area. As is known in the art, theincreased relative humidity leads to discomfort and overhydrated skin,which is prone to skin health problems, especially rashes and othercontact dermatitis.

Generally, liquid impermeable backsheets are well suited to prevent theleakage of bodily fluids (such as urine, menses or fecal matters) fromthe absorbent material to the outer garment of a wearer. However, theuse of such an impermeable backsheet can result in a high degree ofhumidity in the absorbent article when the absorbent article is in usesuch that a relatively elevated skin hydration levels may result.

The problem of high relative humidity near the skin in an absorbentarticle has been addressed in the art through a number of means. Forexample, U.S. Pat. No. 5,137,525 uses mechanical means to increaseairflow in the article. Alternatively, breathable outer cover havingmicroporous or monolithic films may be used in an absorbent article toallow air and water vapor diffusion. PCT Publications WO 98/58609discloses absorbent article using other water vapor permeability, liquidimpermeable barrier materials as the backsheet. PCT Publication WO00/10497, WO 00/10498, WO 00/10499, WO 00/10500, WO 00/10501 relate tobreathable absorbent articles exhibiting the several properties of thedry and wet articles. The absorbent articles disclosed in thesepublications typically have high permeability zones within the absorbentcore, for, example, by aperturing the absorbent core or by varying highabsorbency material content in portions of the core. However, theabsorbent articles include microporous backsheets through which themoisture vapor diffuses from the inside to the outside of the absorbentarticles. The diffusion mechanism is not very effective in removingmoisture vapor. Thus, when the absorbent article is loaded with largeamount of liquids, such as urine, the ineffectiveness of the diffusionthrough a backsheet may result in significantly increased relativehumidity between the skin of the wearer and the article.

Another performance parameter of interest for the loaded/wet absorbentarticle is its ability to hold the liquid and prevent leakage especiallywhen the article is subjected to pressure or impact force applied bywearer's motion, such as sitting, walking, bending, and falling. Theleakage under impact or pressure becomes a serious problem when theabsorbent article is loaded with liquids to near its absorbent capacity.Consequently, it is desirable to have an absorbent article whichexhibits a balance of properties—on one hand it is desirable to keep therelative humidity in the space between the wearer and the absorbentarticle (i.e., the “local” environment) in a comfortable range,typically between about 30% to about 70% and more typically betweenabout 30% to about 50% relative humidity. Further, the absorbent articleshould desirably have the ability to hold liquids without leakage,especially when the article is heavily loaded (i.e., at or near itsabsorbent capacity). It is also desirable to provide an absorbentarticle which manages the relative humidity level within the “local”(i.e., the space between the wearer and the absorbent article)environment by a convective transport mechanism. It is further desirableto provide an absorbent article having a carefully designed combinationof chassis elements such that the “local” conditions (e.g., relativehumidity, skin temperature) are optimized for maintaining or improvingskin health.

Typically, to reduce the humidity level within the space between theabsorbent article and the wearer's skin, breathable polymer films havebeen used as the outer cover for the absorbent article. The breathablefilms are typically constructed with micropores to provide substantialliquid impermeability and some diffusive air/vapor permeability.

Other disposable absorbent articles have been designed to providebreathable regions in the form of breathable panels or perforatedopenings in the backsheet or in the core to help ventilate the garment.Articles using perforated components or breathable panels often exhibitexcessive leakage or wet-through of liquids from the article. Moreover,the wearer's movements (e.g., sitting, falling, walking, lying) maysubject the absorbent article to physical forces, such as impact,compression, bending and the like, which may lead to increased leakageand wet-through. The leakage/wet-through problem becomes more severeunder higher impact or pressure, heavy discharges and/or extended weartime.

Alternatively, multi-layered backsheets or outer covers have been usedto address the wet-through problem. For example, breathable materialssuch as a fibrous textile or a nonwoven web have been used in the outercover, either alone or in laminates with the microporous film. Therelatively open structures of such materials allow air or vapor todiffuse through easily. The laminates may provide improved liquidimpermeability and diffusive air/vapor permeability. The materials maybe treated to further improve the liquid impermeability. However, thelaminates still do not provide satisfactory protection against wetthrough under impact and/or sustained pressure. Further, the transportof air or vapor through the laminates via a diffusive mechanism is notas effective as the transport via a convective mechanism.

An alternative approach to the wet-through problem is to improve theabsorbent material such that little or no liquid comes into contact withthe backsheet, thereby preventing wet-through. This is typicallyachieved by increasing the amount of absorbent material in the article.However, this approach may lead to an increase in thickness of thearticle and a decrease in comfort as well as a decrease in vapor/airpermeability through the article.

Another approach to the wet-through problem is to place formed filmsbetween the core and the backsheet. Formed films having apertures in theshape of slanted cones are disclosed in PCT publications WO 99/39672, WO99/39673 and WO 99/39674. However, after compaction or sustainedpressure, these formed films fail to maintain their formed shape;consequently, they fail to provide the desired balance of properties.The compaction or sustained pressure condition may occur before consumeruse (e.g., during packaging, shipping, and storage), or during use(e.g., when the wearer sits or falls on the absorbent article).

Therefore, it is desirable to have absorbent articles that provideconsumer comfort, in terms of reduced relative humidity within theabsorbent article at a desirable overall thickness, and still achievesatisfactory wet-through protection.

It is also desirable to provide absorbent articles which manage therelative humidity within the space between the article and the wearer'sskin to maintain good skin health. Further, it is desirable to managethe relative humidity within the absorbent article by an effectiveconvective transport mechanism, and, optionally some degree of diffusivetransport mechanism may be incorporated as well.

Additionally, it is desirable to provide absorbent articles wherein anoptimal local i.e., within the space between the article and thewearer's skin) condition for skin health and wearer comfort is achievedby careful designs of components of the article. Specifically, it isdesirable to provide an absorbent barrier structure having the desiredwet-through protection and air/vapor permeability. Further, theabsorbent barrier structure has a desirable thickness for wearercomfort.

It is desirable to provide absorbent articles comprising a barrierabsorbent structure that can be exposed to compact and/or sustainedpressure conditions for at least 24 hours without substantiallydegrading its performance, such as air permeability, liquidimpermeability and resistance to leakage under impact or sustainedpressure.

SUMMARY OF THE INVENTION

The present invention relates absorbent articles with improvedprotection and comfort by use of an absorbent barrier structure. Theabsorbent article of the present invention may comprise an absorbentcore and an absorbent barrier structure, wherein the absorbent barrierstructure may have a hydrohead value of at least about 10 mBars, aconvective air permeability of at least about 10 Darcy/mm, and a liquidimpact transmission (LIT) value of less than about 20 grams per squaremeters.

In one embodiment, the absorbent barrier structure may comprise onebarrier layer disposed adjacent to the garment-facing surface of theabsorbent core, and one reservoir layer disposed adjacent to thegarment-facing surface of the barrier layer. In another embodiment, anadditional barrier layer may be added to the opposite surface of thereservoir layer. In a further embodiment, the absorbent article mayinclude a dampness management layer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is partially broken top plan view of an absorbent articlecontaining the absorbent barrier structure of the present invention;

FIG. 2A is a cross sectional view of an absorbent barrier structure ofthe present invention which has a barrier layer and a reservoir layer;

FIG. 2B is a cross sectional view of an absorbent barrier structure ofthe present invention which has a reservoir layer disposed between twobarrier layers;

FIGS. 3A–3D are cross sectional views of alternative embodiments of theabsorbent barrier structure of FIG. 2A;

FIG. 4A is a top plan view of the absorbent barrier structure of thepresent invention which has a barrier zone and a reservoir zone in aside-by-side arrangement;

FIG. 4B is a top plan view of the absorbent barrier structure of thepresent invention in an alternative arrangement; and

FIGS. 5A–5B are schematic illustrations of the liquid impact testerbefore and during the test.

DETAILED DESCRIPTION OF THE INVENTION

Definitions

As used herein, the term “absorbent articles” refers to devices whichabsorb and contain body exudates, and, more specifically, refers todevices which are placed against or in proximity to the body of thewearer to absorb and contain various exudates discharged from the body.Absorbent articles may include diapers, training pants, adultincontinence undergarments, feminine hygiene products, breast pads, andthe like. As used herein, the term “body fluids” or “body exudates”includes, but is not limited to, urine, fecal matter, blood, vaginaldischarges, and sweat.

The term “disposable” is used herein to describe absorbent articleswhich are not intended to be laundered or otherwise restored or reusedas an absorbent article (i.e., they are intended to be discarded afteruse and, preferably, to be recycled, composted or otherwise disposed ofin an environmentally compatible manner).

As used herein, the term “zone” refers to a region or an area comprisinga material being physically, chemically, or visually distinguishablefrom surrounding or adjoining materials. Various zones of materials mayinclude transitional zones between them. The zones may be positioned inthe z-dimension or in the xy-dimension. As used herein, the term“xy-dimension” refers to the plane orthogonal to the thickness of amember, core or article when the member, core or article is in aflat-out state. The xy-dimension usually corresponds to the length andwidth, respectively, of a structure or an article in a flat-out state.As used herein, the term “z-dimension” refers to the dimensionorthogonal to the length and width of a structure or an article in aflat-out state. The z-dimension usually corresponds to the thickness ofthe structure or article.

As used herein, the term “unitary structure” refers to a structurecomprising materials having different characteristics joined together toform an integral entity such that the materials are substantiallyinseparable physically, and the unitary structure exhibits propertiesresulting from the combination of the materials therein. The materialsmay be arranged in a face-to-face relationship in the z-dimension, or ina side-by-side and/or overlapping relationship in the xy-dimension.

As used herein, the term “operatively associated” refers to a structurecomprising different materials positioned at least in partial contactwith each other in use. The materials are physically separable and eachexhibits properties that can be measured individually. The materials maybe arranged in a face-to-face relationship in the z-dimension, or in aside-by-side and/or overlapping relationship in the xy-dimension.

As used herein, the term “bonded” or “joined” refers to differentmaterials being attached in at least a portion thereof. The attachedportion may be random or may have a pattern such as stripes, spirals,dots, and the like. The attached portion may be located at theperipheries, in the surface area (continuously or discontinuously), orboth. Suitable attachment means known in the art may be used, includingbut not limited to adhesives, heat, pressure, crimping, ultrasonic,chemical (via hydrogen bonds or other cohesive forces), mechanical(e.g., fasteners, entanglements), hydraulic, vacuum and combinationsthereof.

As used herein, the term “composite structure” refers to a multi-zonedstructure wherein the materials comprising the zones may be operativelyassociated or bonded. The zones may even be in intimate contact suchthat the composite has a unitary structure. Further, the zones may bepositioned in a layered (face-to-face) arrangement, or a side-by-sideand/or overlapping arrangement

As used herein, the term “absorbent core” refers to the component of theabsorbent article that is primarily responsible for fluid handlingproperties of the article, including acquiring, transporting,distributing and storing body fluids. As such, the absorbent coretypically does not include the topsheet, backsheet or outer cover of theabsorbent article.

As used herein, the term “nonwoven web” refers to a web that has astructure of individual fibers which are interlaid to form a matrix, butnot in an identifiable repeating manner. Nonwoven webs may be formed bya variety of processes known to those skilled in the art, for example,meltblowing, spunbonding, wet-laying, air-laying, and variousbonding-carding processes.

The present invention relates to absorbent articles with improvedprotection and comfort by use of an absorbent barrier structure. This isachieved by the selection of individual components meeting specificrequirements such that the combination thereof provides the absorbentarticles with the desired performance.

A typical absorbent article of the present invention may comprise anair/vapor permeable, liquid impermeable outer cover, a liquid permeablebodyside liner or topsheet, an absorbent core between the outer coverand the bodyside liner, and an absorbent barrier structure positionedbetween the outer cover and the absorbent core.

The absorbent barrier structure of the present invention balances theproperties of convective air flow and absorptive barrier property. Theconvective air flow property is effective in reducing the relativehumidity within the space between the absorbent article and the wearer'sskin. The combination of liquid absorption and the liquid barrierproperty provides protection against the wet-through problem, and isespecially beneficial when the absorbent article is under impact and/orsustained pressured conditions.

The absorbent barrier structure is a composite structure having at leastone barrier zone and at least one reservoir zone. The barrier zone isresistant to liquid penetration so that the outflow of liquids from theabsorbent core is substantially slowed or retarded to allow additionaltime for the absorbent core to acquire, distribute and retain theliquids to its full absorbent capacity. Suitable materials for thebarrier zone should have a hydrohead value of at least about 10 mBars.The reservoir zone absorbs and retains any errant liquid that escapesboth the core and the barrier zone, and thus, provides added protectionagainst wet-through. The zones of the absorbent barrier structureprovide a combination of properties, which effectively protect againstthe wet-through problem, even under extreme conditions, such as impactor sustained pressure.

The following detailed description of the absorbent barrier structure ofthe present invention is in the context of a disposable diaper. However,it is readily apparent that the absorbent barrier structure of thepresent invention is also suitable for use in other absorbent articlessuch as feminine hygiene products, training pants, incontinencearticles, and the like. It is also apparent that the absorbent barrierstructure of the present invention is suitable for use in other hygieneor health care products, such as bandages, dressings, wipes, bibs,surgical drapes, surgical gowns, and the like.

The Barrier Structure or the Absorbent Barrier Structure

The present invention provides a barrier structure which allowsconvective transport of air or water vapor though this structure.Particularly, the structure of the present invention achieves thedesirable convective air flow capacity without sacrificing the barrierprotection against wet-through. When the barrier structure is includedin an absorbent article, the resulting absorbent article shows effectivereduction of the relative humidity in the space between the absorbentarticle and the wearer. Consequently, the barrier structure reducesincidents of skin irritation and/or rash and improves skin health andwearer comfort.

Convective transport capacity is different from the diffusive transportcapacity. The convective transport is driven by a gas or air pressuredifferential and is typically at a much higher transport rate than thediffusive transport, which is driven by random molecular movements. Atypical example of diffusive transport includes the moisture migrationthrough the pores of a microporous films such as those known in the artas the backsheet materials, or through the molecular structure of anonporous monolithic film such as that made from HYTREL® (available fromDuPont, Wilmington, Del.). Convective transport, on the other hand, isdirected by the air pressure differential between the inside and theoutside of the article. Though the local pressure (i.e., the localpressure within the space between the article and the wearer) and thepressure of the environment (i.e., outside the article) aresubstantially the same, small changes in the local pressure may lead toconvective air/vapor flow towards the outside of the article. Factorsthat may lead to convective transport include, but are not limited to,movements by the wearer, small pressure and/or temperature differentialbetween the local and the outside environment, and the like.

With the advances made to absorbent articles using elastic materials andelastic components, the absorbent articles now provide a tighter seal(i.e., less gapping) against the wearer's body to minimize fluid leakageto the outside. Consequently, the convective air flow through the gapsis substantially reduced, leading to a humid and hot local environment.While absorbent cores typically have some air permeability; the airpermeability typically is reduced when the cores absorb liquid (i.e.,become loaded). The loaded cores can be vented (i.e., made airpermeable) relatively easily, typically by venting means, such as holes,baffles, and the like. Alternatively, openness of the core structurescan be achieved by selected arrangements of permeable materials.

These vented or open-structured cores generally require a leakageprotection component, which is typically a microporous film backsheet ora relatively thick nonwoven fabric that provides liquid impermeabilityand/or leakage protection. However, these liquid impermeable componentsmay reduce the air permeability of the article. In contrast, the barrierstructure of the present invention allows the convective air flowthrough the structure itself without sacrificing leakage protectionproperty.

In some embodiments, the barrier structure of the present invention alsoprovides liquid absorbency and good liquid retention capability. Thus,it is also an absorbent barrier structure. The liquid retentioncapability is especially beneficial when wearer's motions, such assitting, falling, lying, bending, walking, may apply pressure/forces onthe loaded (i.e., wetted with bodily fluids) absorbent body and/or theadjacent absorbent barrier structure and may lead to leakage orwet-through. Thus, when the absorbent barrier structure is included inan absorbent article, the resulting absorbent article not only provideseffective convective air flow capacity, but also provides effectiveprotection against wet-through, even when the article is subjected topressure or impact forces.

Typically, the absorbent barrier structure is positioned between theabsorbent core and the outer cover, preferably adjacent to thegarment-facing side of the absorbent core. The absorbent barrierstructure is a composite structure, which comprises a plurality ofindividual zones of materials that are joined or operatively associatedtogether. Alternatively, the plurality of zones may be combined into aunitary structure such that the individual zones become physicallyinseparable. The individual zones of the absorbent barrier structure maybe coextensive or non-coextensive, depending on the requirements of theabsorbent article. The individual zones may be joined by attachmentmeans such as those well known in the art.

In some embodiments, a member is directly bonded to the other member byaffixing the member directly to the other member. In other embodiments,a member is indirectly secured to the other member by affixing onemember to intermediate member(s), which in turn are bonded to the othermember. For example, the zones may be bonded together by a uniformcontinuous layer of adhesive, or an array of separate lines, spirals, ordroplets or beads of adhesive. The adhesive may be applied continuouslyor intermittently. For example, each application of the adhesive spansthe length of the absorbent barrier structure and is separated from oneanother by a selected distance. The adhesive is applied to tack thezones together for handling the webs in the assembly process.Preferably, the adhesive is applied to portions of the surface of theabsorbent barrier structure, leaving sufficient open (i.e., free ofadhesives) surface areas for air/vapor permeability. Alternatively, theadhesive may be applied to modify the liquid impermeability. Typically,the open or adhesive-free surface area is no less than about 50%,preferably no less than about 70%, more preferably no less than about80%, and most preferably no less than about 90% of the total surfacearea of the absorbent barrier structure. Suitable adhesives may beHL-1258 from H.B. Fuller Company of St. Paul, Minn., and H2031 F fromAto-Findley Inc. of Milwaukee, Wis.

In one embodiment, the adhesive may be applied in one or more stripsalong the peripheries of the zones. In another embodiment, the adhesivemay be applied in spaced-apart stripes aligned with the longitudinalcenterline of the diaper when it is used in a diaper. In anotherembodiment, the adhesive may be applied to the web in three stripesalong the longitudinal centerline of the diaper. Each stripe is 22 mmwide (in the lateral direction of the diaper) and the two outer stripesare disposed at or near (about 4 mm from) the longitudinal peripheries.

The adhesive is typically applied from its softened or melted state tothe surface of at least one of the materials comprising the absorbentbarrier structure. Typically, the adhesive is heated to at least aboveits softening temperature prior to being applied to a substrate surface.Once applied, the adhesive is allowed to cool and harden/solidify.Various methods for softened or melted state application of adhesivesare known. Methods particularly suitable for use herein include, but arenot limited to, spraying, dipping, gravure printing, and extrusion.

Alternatively, the attachment means may comprise heat bonding, pressurebonding, ultrasonic bonding, mechanical bonding (via, for example,entanglements, cohesive forces, electric or static charges), hydraulicneedling or any other suitable attachment means or combinations of theseattachment means as are known in the art.

The individual zones may be arranged in layers, wherein individual zonesare in an operable, intimate contact with at least a portion of theadjacent layer. Such contacts may be random, or may have a regularpattern, such as dots, stripes, and the like. Preferably, each layer isconnected to at least a portion of an adjacent layer of the absorbentbarrier structure by a suitable bonding and/or attachment means. Inanother embodiment, the individual zones may be arranged in an operable,intimate contact along at least a portion of its peripheries with theadjacent layer of the absorbent barrier structure.

The absorbent barrier structure of the present invention may beconstructed to have a convective air permeability of at least about 1Darcy/mm, preferably at least about 10 Darcy/mm, more preferably atleast about 30 Darcy/mm, and most preferably at least about 50 Darcy/mm.Convective air permeability is especially effective in removing moisturevapor from inside the absorbent article, resulting in a lower humidityin the local environment next to the skin.

Though the liquids are mainly absorbed by the absorbent core, theabsorbent barrier structure provides additional leakage protectionagainst errant liquids that are not absorbed by or are released from theabsorbent core. Thus, the absorbent barrier structure of the presentinvention preferably has at least some liquid absorbency.

Liquid absorbency may vary, depending on the materials used in theabsorbent barrier structure, the surface tension of the liquid beingtested for absorbency, and the contact angle between the test liquid andthe material. An absorbent barrier structure suitable for use hereintypically has an absorbency (as measured by Test Method G using a 0.2 wt% Triton® solution) of at least about 1 g/g, typically from about 1 toabout 100 g/g, preferably from about 5 to about 50 g/g, more preferablyfrom about 10 to about 30 μg.

Further, the absorbent barrier structure of may also have a liquidretention capability, in order to provide the additional leakageprotection, especially under impact and/or sustained pressureconditions. The absorbent barrier structure may have a liquid impacttransmission value (as measured by Test Method C) of less than about 20g/m², preferably less than about 15 g/m², more preferably less thanabout 10 g/m², and most preferably less than about 6.5 g/m².

Also related to the leakage protection performance, it is desirable thatthe absorbent barrier structure has a certain degree of resistance toliquid penetration. Thus, the absorbent barrier structure may have ahydrohead value (as measured by Test Method B) of at least about 10mBars, preferably at least about 30 mBars, more preferably at leastabout 50 mBars, and most preferably at least about 75 mBars. In someembodiments, the absorbent barrier structure may have a hydrohead valuein the range from about 30 to about 100 mBars.

It is also desirable that the absorbent barrier structure providesleakage protection in terms of a static liquid transmission value(measured according to Test Method D). In this respect, the absorbentbarrier structure of the present invention has a static liquidtransmission value of less than about 45 g/m², preferably less thanabout 30 g/m², more preferably less than about 20 g/m², and mostpreferably less than 13 g/m², at 15 minutes after impact. Further, theabsorbent barrier structure of the present invention has a static liquidtransmission value of no more than about 50 g/m², preferably no morethan about 35 g/m², more preferably no more than about 20 g/m², at 60minutes after impact.

In another aspect, after the absorbent barrier structure has beensubjected to the compaction condition such as that described below inthe Test Method F, it does not suffer substantial changes in barrierproperties. The structural integrity during compaction and recoveryafter compaction are desirable for practical purposes. The absorbentarticles are typically compacted into a package for shipping andstorage. When the articles are eventually removed from the compactionfor the intended use, the material or structure that fails to recover toits pre-compaction state may fail to provide the properties it wasoriginally designed for. Thus, the absorbent barrier structure of thepresent invention desirably has a post-compaction air permeabilitydecrease of no more than 35%, preferably no more than 25% decrease andmost preferably no more than 15% decrease, compared to itspre-compaction air permeability. In a preferred embodiment, theabsorbent barrier structure has the post-compaction air permeability asdisclosed above, after 7 days, preferably after 30 days, more preferablyafter 90 days.

The thickness and basis weight of the absorbent barrier structure mayvary, depending on the materials used, the properties desired, theintended use, the construction, and the like. For example, thicknessand/or basis weight may affect the diffusive breathability and/or theconvective air permeability between the interior of an article and theoutside, the absorbency and/or leakage protection of the article, thefit of the article to the wearer's body, the wearer's comfort, and likeeffects that typically relate to thickness of a structure. Typically,the absorbent barrier structure of the present invention intended foruse in an absorbent article has a thickness of less than about 1.5 mm,preferably less than about 1.2 mm, and more preferably less than about1.0 mm. The thickness of the absorbent barrier structure suitable foruse in an absorbent article should also have a minimal thickness greaterthan about 0.1 mm, preferably greater than about 0.2 mm. Further, theabsorbent barrier structure of the present invention suitable for use inan absorbent article typically has a basis weight in the range of fromabout 20 gsm (g/m²) to about 200 gsm (g/m²), preferably from about 30gsm (g/m²) to about 150 gsm (g/m²), more preferably from about 40 gsm(g/m²) to about 120 gsm (g/m²), and most preferably from about 50 gsm(g/m²) to about 100 gsm (g/m²).

The absorbent barrier structure typically comprises two zones: a barrierzone and a reservoir zone. The barrier zone is “substantiallyimpermeable” to liquids, including water, urine, menses, and otherbodily fluids. The term “substantially impermeable” means that thebarrier zone exhibits a resistance to liquid penetration but does notnecessarily eliminate liquid wet-through. In other words, it is possiblefor liquid to penetrate and flow through the barrier zone under certainconditions, such as under impact force, under high applied pressure, orunder sustained (i.e., continuously applied) pressure for a period oftime. The reservoir zone is liquid absorbent. When the reservoir zone ispositioned adjacent to the barrier zone, any wet-through and/or leakagefrom the barrier zone may be absorbed by the reservoir zone. Inaddition, the reservoir zone may also absorb errant liquids from theabsorbent core. Thus, the combination of the barrier zone and thereservoir zone achieves the unique balance of properties that, whenexposed to liquids, the barrier zone provides a resistance to liquidwet-through, and the reservoir zone absorbs any errant liquids thatbreak through the resistance of the barrier zone. That is, the absorbentzone provides the added protection against the liquid wet-throughproblem. When the absorbent barrier structure of the present inventionis positioned adjacent to a loaded absorbent core, it provides theadditional protection against wet-through, particularly when the liquidloading level is high and/or the loaded absorbent core is under asudden, high impact force or sustained forces/pressure.

This additional wet-through protection is especially beneficial forabsorbent articles used in high liquid loading applications (e.g.,diapers, training pants, pull-on diapers, or adult incontinenceproducts). The wet-through protection is also beneficial when theabsorbent articles are subjected to sudden impact or sustained pressure(e.g., when babies or adults fall, sit down, roll, sleep).

The absorbent barrier structure of the present invention is alsobeneficial when the absorbent core is subjected to gushes of liquids.The resistance to liquid wet-through provides by the barrier zone servesto temporarily slow down the gushes of liquids, possibly pooling theliquids at the interface between the absorbent core and the barrierzone. The slowed flow and pooling provide the additional time for theabsorbent core to acquire and distribute the liquids to other regions ofthe core beyond the point of insult. Consequently, the absorbent coremay achieve its full absorbent capacity.

Exemplary absorbent barrier structure of the present invention areillustrated in the following figures. FIG. 2A is a cross sectional viewof an embodiment of the absorbent barrier structure of this invention.The absorbent barrier structure 10 comprises a barrier layer 12 and areservoir layer 14. In another embodiment, as shown in FIG. 2B, anadditional barrier layer 16, may be disposed on the other side of thereservoir layer 14 such that the reservoir layer 14 is sandwichedbetween the barrier layers 12 and 16. The first and the second barrierlayers may be made of identical or different (in terms of constructionof the web, basis weight, thickness, porosity, fiber denier, material,and the like) fibrous webs.

Various arrangements of the barrier zone and the reservoir zone areshown in FIGS. 3A–3D. In FIG. 3A, multiple barrier zones 12 andreservoir zones 14 are arranged in a side-by-side relation, wherein thebarrier zones 12 and the reservoir zones 14 are preferably stripes. InFIG. 3B, the barrier zone 12 is a continuous web and the reservoir zone14 is disposed adjacent thereto in a discontinuous pattern, such asstripes, circles, ellipses, squares, and the like. In FIG. 3C, thereservoir zone 14 is a continuous web and the barrier zone 12 isdisposed adjacent thereto in a discontinuous pattern, such as stripes,circles, ellipses, squares and the like. In FIG. 3D, the discontinuousbarrier zones 12 overlap at least partially with the discontinuousreservoir zones 14, and each may have the shape of stripes, circles,ellipses, squares, and the like.

In all of the embodiments illustrated in FIGS. 2A–3D, at least a portionof the barrier zone is positioned adjacent to the garment-facing side ofthe absorbent core. In one embodiment, the absorbent barrier structuremay be substantially coextensive with the absorbent core. Alternatively,the absorbent barrier structure may be stripes or patches that extendonly to portions of the absorbent core. In another embodiment, theabsorbent barrier structure may extend beyond the outer edges of theabsorbent core or only through the length and width of the centralportion of the absorbent core. In one embodiment, the barrier zone andthe reservoir zone are arranged in a layered relation, wherein thebarrier layer is disposed immediately adjacent to the garment-facingside of the absorbent core. Configurations in which the barrier zone hasat least the same length and width of the absorbent core are desirable.Furthermore, the reservoir zone need not have the same dimensions as thebarrier zone.

The Reservoir Zone

The reservoir zone desirably absorbs, spreads and retains liquids suchas urine, blood and other body exudates. The reservoir zone has agarment-facing surface, a body-facing surface, front and rear edges, andside edges. The reservoir zone absorbs and retains the errant liquidsthat escape from other components such as the absorbent core and thebarrier zone. Thus, the reservoir zone provides additional protectionagainst wet-through.

The thickness and basis weight of the reservoir zone may vary, dependingon the materials used, the properties desired, the intended use, theopenness of the construction, and the like. Specifically, the thicknessof the reservoir zone may affect the air/gas permeability, theabsorbency and/or leakage protection of the barrier absorbent structure,as well as the comfort and fit of the absorbent article, and likeeffects typically related to the thickness of a structure. Thus, thereservoir zone typically has a thickness of less than about 1.5 mm,preferably less than about 1.0 mm, and more preferably less than about0.8 mm. The reservoir zone may desirably have a minimal thickness toprovide for adequate absorbency and structural integrity. The minimalthickness of the reservoir zone is typically no less than about 0.2 mm,preferably no less than about 0.1 mm, more preferably no less than 0.05mm, and most preferably no less than 0.02 mm. Further, the basis weightof the reservoir zone is typically in the range from about 5 gsm (g/m²)to about 120 gsm (g/m²), preferably from abut 10 gsm (g/m²) to about 100gsm (g/m²), and more preferably from about 30 gsm (g/m²) to about 80 gsm(g/m²).

When compared to the absorbent core, the reservoir zone absorbs fluidsmore readily (i.e., a faster fluid uptake) and releases fluids morereadily. The reservoir zone typically has an absorbency of at leastabout 1 g/g, preferably at least about 5 g/g, more preferably at leastabout 10 g/g, based on Test Method G and using 0.2 wt % TRITON® as thetest fluid. The absorbency of the reservoir zone is preferably less thanabout 30 g/g, and more preferably less than about 20 g/g. Further, thereservoir should have an absorbency that is less than that of theabsorbent core by at least about 20%, preferably by about 30%.

The reservoir zone may desirably have an open structure such that itsair or gas permeability is at least equal to that of the resultingabsorbent barrier structure. The convective air/vapor permeability ofthe reservoir zone is typically at least about 1 Darcy/mm, preferably atleast about 10 Darcy/mm, more preferably at least about 30 Darcy/mm, andmost preferably at least about 50 Darcy/mm.

Further, the openness of the structure may enhance absorbency by holdingor absorbing the fluids in the interstitial spaces in the openstructure. Suitable open structures may include fibrous webs (e.g.,woven or nonwoven webs); absorbent foams (e.g., porous or reticulatedfoams); fibrous wads; and the like.

In one embodiment, the reservoir zone is made of fibrous webs. Thefibrous webs constituting the reservoir zone need not necessarilycomprise absorbent fibers, so long as the webs are absorbent. Thus, theconstituent fibers may simply be hydrophilic fibers and have noabsorptive capacity by themselves.

In one embodiment, the reservoir zone is made of primarily cellulosicfibers which are primarily hydrogen bonded to one another. Cellulosicfibers may be natural or processed, and may be chemically stiffened,modified or cross-linked. Processed cellulosic fibers may includecommercially available fibers made of regenerated cellulose orderivatized cellulose, such as Rayon. In another embodiment, thereservoir zone may comprise at least about 70 wt % of cellulosic fibers,preferably at least about 80 wt % and more preferably at least about 90wt %. Alternatively, the reservoir zone may comprise from about 95 to100 wt % cellulosic fibers.

In another embodiment, the reservoir zone may be in the form of a singleor multi-ply tissue; a creped tissue; a tissue wadding; or an airfeltmat. High wet strength tissue may also be used as the reservoir zone. Inanother embodiment, the reservoir zone may be of any form having an openstructure whereby the bodily fluids are held or absorbed in the fineinterstitial spaces in the open structure. Further, inter-ply spaces andsurface textures may provide additional interstitial, liquid holdingcapacities, which enhance the absorbency of the reservoir zone.

The reservoir zone may include supplemental chemical bonding agents thatare well known in the art. For example, the reservoir zone may include achemical bonding agent such as vinyl acrylic copolymers, polyvinylacetate, crosslinkable polyamides, polyvinyl alcohol and the like.Additionally, wet strength resins and/or resin binders may be added toimprove the strength of the cellulosic web. Useful binders and wetstrength resins include commercially available resins, for example,KYMENE®, available from Hercules Chemical Company and PAREZ® availablefrom American Cyanamid, Inc. Crosslinking agents and/or hydrating agentsmay also be added to the pulp mixture to reduce the degree of hydrogenbonding if an open or loose fibrous web is desired. An exemplarydebonding agent is available from Quaker Chemical Company, Conshohocken,Pa., under the trade name Quaker 2008. The reservoir zone may contain nomore than 5 weight percent and optionally may contain no more than about2 weight percent of the chemical bonding agent. The reservoir zonetypically comprises a high wet strength tissue. Alternatively, thereservoir zone may comprise a synthetic fibrous web. The reservoir zonemay be bonded, such as with adhesives, to the barrier zone or othercomponents of the diaper construction.

Suitable materials for the reservoir zone may comprise a primarilycellulosic fibrous web, such as commercially available consumer papertowels BOUNTY®, manufactured by The Procter & Gamble Company,Cincinnati, Ohio, or HI-DRY®, manufactured by The Kimberly-ClarkCorporation.

Suitable fibrous webs may have a single-ply or a multi-ply construction.As used herein, the term “ply” means individual webs being disposed in asubstantially contiguous, face-to-face relationship, forming a multiplelayered web. Further, a single web may form two plies, for example, byfolding on itself. In a multi-ply construction, the individual webs areat least partially joined, typically via point bonding, with or withoutadhesives.

It is found that the multi-ply construction provides higher resistanceto liquid breakthrough than a single-ply construction on a unit weightbasis (gram per square meter). Further, the absorbency of a two-plyfibrous web is at least double that of the single-ply fibrous web, on aunit weight basis. Without being bound by theory, it is believed thatthe interstitial spaces (i.e., structural voids) between the pliesprovide additional liquid holding space, consequently, a higherabsorptive capacity. Furthermore, post-treatments of the cellulosic web,including, but not limited to, aperturing, creping, embossing, orotherwise texturizing, increase the absorbency of the web. Fibrous webshaving apertured or texturized surfaces show higher absorptive capacity,possibly due to the microvoids and/or interstitial spaces created by thetreatments. In one embodiment, the reservoir zone is made from a fibrousweb having a construction of at least two plies and a texturizedsurface. Additionally, certain additives, such as debonding agents, mayalso increase the absorbency of the web by reducing the inter-fiberbondings (e.g., hydrogen bonds between cellulosic fibers), thus,loosening the compacted fibrous network in the webs. The openness of theresulting web provides more interstitial spaces to hold liquids andenhances the absorbency of the web.

In an alternative embodiment, other types of wettable and/or hydrophilicfibrous materials may be used to form the reservoir zone of theabsorbent barrier structure. Exemplary fibers include naturallyoccurring organic fibers made from intrinsically wettable material, suchas cellulose or processed cellulose fibers, including regenerated orderivatized cellulose fibers commercially available as Rayon® fiber,Viscose® fibers; synthetic fibers made from inherently wettablethermoplastic polymers, such as polyesters, polyamides, theircopolymers, polyvinyl alcohols, polyalkylene oxides, and mixtures ofthese polymers; and synthetic fibers made from a nonwettablethermoplastic polymers, such as polyethylene, polypropylene,polybutylene and other polyolefins, which may be hydrophilized byappropriate means. These nonwettable fibers may be hydrophilized bytreatments with surfactants or surface-active agents having suitablehydrophilic functionalities, or by sheathing. These nonwettable fibersmay also become of more wettable by grafting hydrophilic functionalitiesonto the polymer chains. Suitable hydrophilic functionalities include,but are not limited to, acrylic, methacrylic, ester, amide, and mixturesthereof. Combination fibers such as bi-component fibers, sheathedfibers, are also suitable for use herein.

The reservoir zone may contain additives such as chemical bondingagents, crosslinking agents, wet strength resins, debonding agents,liquid or moisture absorbing agents, odor absorbing agents,antimicrobials, coloring agents, stiffening agents, and mixturesthereof. The liquid or moisture absorbing agents, include, but are notlimited to, clays, silicas, talc, diatomaceous earth, perlite,vermiculite, carbon, kaolin, mica, barium sulfate, aluminum silicates,sodium carbonate, calcium carbonate, other carbonates, superabsorbentpolymers or other osmotic liquid holding agents, and mixtures thereof.

In one embodiment, the reservoir zone additionally containssuperabsorbent polymers, which are coated onto the fibers, blended intothe fibers in-situ, or are made into fibers or particles.

The Barrier Zone

The barrier zone preferably has a “barrier-like” property (i.e.,resistance to liquid wet-through). The barrier property is typicallymeasured by the Test Method B described below. It is desirable that thehydrohead value of the barrier zone should be higher than that of theabsorbent core and of the reservoir zone. The barrier zone materialsuitable for use herein typically exhibits a hydrohead value of at leastabout 10 mBars, preferably at least about 30 mBars, more preferably atleast about 50 mBars, and most preferably at least about 75 mBars. Insome embodiments, the suitable barrier zone has a hydrohead value in therange from about 30 to about 100 mBars.

It is also desirable that the barrier zone substantially reduces theair/vapor permeability of the absorbent article. In that respect, thebarrier zone typically has a convective air permeability of at leastabout 10 Darcy/mm and preferably at least about 30 Darcy/mm.

The hydrohead value of a fibrous web increases with finer fiberdiameter, higher fiber density, higher basis weight, or combinationsthereof. Suitable fibrous webs for the barrier zone typically have abasis weight of at least about 2 gsm, preferably from about 5 to about100 gsm, more preferably from about 10 to about 75 gsm, and mostpreferably from about 15 to about 55 gsm.

The thickness of the barrier zone may vary, depending on the materialsused, the properties desired, the intended use, the construction, andthe like. Specifically, the thickness of the barrier zone may affect theair/gas permeability, the absorbency and/or leakage protection of thebarrier absorbent structure, as well as the comfort and fit of theabsorbent article, and like effects typically related to the thicknessof a structure. Thus, the barrier zone typically has a thickness of lessthan about 1.5 mm, preferably less than about 1.0 mm, more preferablyless than about 0.8 mm, and most preferably less than about 0.5 mm.

It has been found that some materials which do not appreciably limit theair permeability of the absorbent article in the dry state willsignificantly decrease the air permeability of the article when theabsorbent core becomes loaded with liquids. Thus, suitable materials foruse in the barrier zone should allow sufficient water vaportransmission, when the absorbent article is in a dry state. It isdesirable that the air/water vapor permeability of the absorbent articledoes not change substantially from that of an equivalent diaper withoutthe barrier zone material. However, when the absorbent core becomesloaded from absorbing liquids discharged from the body, the barrier zonemay lower the air/vapor permeability of the absorbent article (relativeto an equivalent article without a barrier zone), thereby reducing oreliminating the dampness which may develop on the garment side of theouter cover.

In order to provide the desired hydrohead value or the “barrier-like”property, suitable materials are preferably hydrophobic, though this isnot a required characteristic. Exemplary hydrophobic polymeric materialsare typically polyolefins, such as polyethylene, polypropylene,polybutylene and copolymers thereof. Materials that are not hydrophobic,such as polyamides, polyesters, polyalkylene oxides, polyvinyl alcohols,may be treated by suitable hydrophobic agents to achieve the desiredhydrophobicity. Additionally, the reservoir layer may also be treated onat least one surface to improve its hydrophobicity, hence, its barrierproperty.

Treatments for improved hydrophobicity may include chemical, radiation,plasma or combinations thereof. Further, the surface treatment to modifythe surface characteristics may be accomplished by a coating on thesurface, by pre-blending with a hydrophobic agent or by incorporating ahydrophobic agent in-situ, which blooms to the surface by furtherprocessing.

In one embodiment, fluorocarbon treatment of the web material mayprovide the desired hydrophobicity such that the web exhibits thedesired water resistance characteristics, measured, for example, by TestMethod B. In another embodiment, fluorocarbon treatment using plasma orlike technology may provide a very thin, hydrophobic coating such thatthe air permeability of the treated web is substantially unchanged. Ifdesired, the treatment may be applied to only portions of the substratesurface. These treatments may be applied to different components of theabsorbent article, including but are not limited to the barrier zone,the reservoir zone, the outer cover, or other diaper components.Suitable substrate materials for this treatment include, but are notlimited to, nonwoven webs, cellulosic webs, thermoplastic films,modified/processed films (e.g., formed, apertured) and the like.Exemplary surface treatments using fluorocarbons are described in U.S.Pat. No. 5,876,753, issued to Timmons et al. on Mar. 2, 1999; U.S. Pat.No. 5,888,591 issued to Gleason et al. on Mar. 30, 1999; U.S. Pat. No.6,045,877 issued to Gleason et al. on Apr. 4, 2000; PCT PatentApplication 99/20504 by D'Agostino et al., published on Sep. 7, 1999(corresponding to U.S. Pat. No. 6,649,222); PCT Publication 00/14296 byD'Agostino et al., published on Mar. 16, 2000 (corresponding to U.S.Ser. No. 09/786075); the disclosures of each is hereby incorporated byreference.

Other surface coating methods using silicones or fluoro chemicals areknown in the art and may be used herein. The conventional coating orsurface treatment methods typically fill the voids within the web, andthus, lowers its air permeability. Coating methods to providehydrophobicity to the substrate without the decrease in air permeabilitycan be found in U.S. Pat. No. 5,322,729, the disclosure of which ishereby incorporated by reference.

The barrier zone may comprise fibrous web materials such as nonwovenwebs including, but not limited to, meltblown (MB) webs; spunbond (SB)webs, particularly fine fiber spunbond webs such as those having fiberdeniers of about 2 or less; composite webs having layers of meltblownand spunbonded fibers, commonly known as MS nonwovens, and SMSnonwovens; bonded and carded webs; air laid webs; hydro-entangled webs;knitted webs; and woven webs.

Nonwoven webs having the desired combination of high liquid resistanceand high air permeability are typically made by the melt blowingprocess. Nonwoven webs comprising low denier fibers and/or uniformdistribution of fine fibers are desirable.

In one embodiment, the barrier zone comprises a meltblown web ofpolypropylene fibers having a basis weight of from about 4 to about 80g/m², preferably from about 6 to about 70 g/m², more preferably fromabout 8 g/m² to about 50 g/m², and most preferably from about 10 toabout 30 g/m².

The meltblown fibers typically have an average diameter in the range ofless than about 20 microns, preferably less than about 10 microns. Mosttypically, the meltblown fibers have an average fiber diameter in the 5to 10 microns range. Also suitable for use herein are nanofibers havingan average fiber diameter in the range of less than about 500nanometers, preferably less than about 300 nanometers, and morepreferably less than about 150 nanometers. Exemplary nonwoven webs madefrom nanofibers (having average fiber diameters from about 10 to about100 nanometers) are available from E-Spin Technologies (Chananooga,Tenn.).

While the strength of the meltblown nonwoven web generally decreaseswith decreasing fiber denier, the strength can be improved by laminationwith a reinforcing scrim or web such as tissues, paper towels, orspunbonded nonwoven webs. Any conventional lamination process may beused, including adhesive bonding, thermal boning, ultrasonic bonding,calendaring, needling, and combinations thereof. However, the laminationprocess should be carefully exercised to minimize adverse effects on theair permeability of the resulting laminate. In one embodiment, themicrofiber nonwoven web may be integrally laminated during themanufacture by direct melt blowing onto another reinforcing scrim orweb.

The fibrous barrier zone may comprise a single web or multiple layers ofwebs which collectively have the desired characteristics. However, whenusing multiple layers of webs, it is desirable that they are juxtaposedwithout being point bonded across a substantial surface area of thezones or otherwise bonded in a manner which would substantially limitthe breathability of the zones. When joining the barrier zone to theabsorbent core and/or the reservoir zone, it is desirable that thebreathability of the article is maintained. In this regard, it may bedesirable that the barrier zone be attached to other components theabsorbent article (such as the absorbent core, the reservoir zone)primarily at the peripheries of the barrier zone. The multiple zones canbe joined by heat, pressure, ultrasonic, adhesive or by other meansknown in the art.

The barrier zone may contain additives such as chemical bonding agents,crosslinking agents, liquid or moisture absorbing agents, odor absorbingagents, antimicrobials, coloring agents, stiffening agents, and mixturesthereof. The liquid or moisture absorbing agents, including, but notlimited to, clays, silicas, talc, diatomaceous earth, perlite,vermiculite, carbon, kaolin, mica, barium sulfate, aluminum silicates,sodium carbonate, calcium carbonate, other carbonates, superabsorbentpolymers or other osmotic liquid holding agents, and mixtures thereof.

Absorbent Article Components

FIG. 1 is a partially broken top plan view of a diaper 20 containing theabsorbent barrier structure 10 of the present invention. The diaper 20is in a flat-out state with portions of the structure cut away to moreclearly show the construction of the diaper 20. The garment-facingsurface of the diaper 20 is oriented away from the viewer.

As shown in FIG. 1, the diaper 20 comprises a liquid pervious topsheet24; a dampness management means 26; an absorbent core 28, which ispositioned between at least a portion of the topsheet 24 and the outercover 22; an absorbent barrier structure 10 positioned between theabsorbent core 28 and the outer cover 22; side panels 30; elasticizedleg cuffs 32; elastic waist features 34; and a fastening system 40. Anabsorbent barrier structure 10 of the present invention is disposedadjacent to the absorbent core 28 on the garment facing surface of theabsorbent core 28.

Diaper 20 is shown in FIG. 1 to have a front waist region 36, a rearwaist region 38 opposed to the front waist region 36 and a crotch region37 located between the front and the rear waist regions. The peripheriesof the diaper 20 are defined by the outer edges of the diaper 20 inwhich the longitudinal edges 50 run generally parallel to thelongitudinal centerline 100 of the diaper 20 and end edges 52 runbetween the longitudinal edges 50 generally parallel to the lateralcenterline 110 of the diaper 20.

The main body of the diaper 20 comprises at least the absorbent core 28,the topsheet 24, and preferably, though not necessarily, the dampnessmanagement means 26. An outer cover 22 forms the chassis, onto whichother components of the diaper 20 are added to form the unitarystructure of the diaper.

FIG. 1 shows an embodiment of the diaper 20 in which the topsheet 24 andthe dampness management means 26 have length and width dimensionsgenerally no smaller than those of the absorbent core 28 and theabsorbent barrier structure 10. The topsheet 24 and the dampnessmanagement means 26 may extend to the peripheries of the diaper 20. Inanother embodiment, the absorbent barrier structure 10 may extend beyondthe edges of the absorbent core 28 to the peripheries of the diaper 20.

While the components of the diaper 20 may be assembled in various wellknown configurations, preferred diaper configurations are describedgenerally in U.S. Pat. No. 3,860,003 entitled “Contractible SidePortions for Disposable Diaper” issued to Kenneth B. Buell on Jan. 14,1975; U.S. Pat. No. 5,151,092 issued to Buell on Sep. 9, 1992; and U.S.Pat. No. 5,221,274 issued to Buell on Jun. 22, 1993; and U.S. Pat. No.5,554,145 entitled “Absorbent Article With Multiple Zone StructuralElastic-Like Film Web Extensible Waist Feature” issued to Roe et al. onSep. 10, 1996; U.S. Pat. No. 5,569,234 entitled “Disposable Pull-OnPant” issued to Buell et al. on Oct. 29, 1996; U.S. Pat. No. 5,580,411entitled “Zero Scrap Method For Manufacturing Side Panels For AbsorbentArticles” issued to Nease et al. on Dec. 3, 1996; and U.S. Pat. No.6,004,306 entitled “Absorbent Article With Multi-Directional ExtensibleSide Panels” issued to Robles et al. on Dec. 21, 1999; each of which isincorporated herein by reference.

Topsheet or Body-Side Liner

The topsheet is compliant, soft feeling, and non-irritating to thewearer's skin. The topsheet material can also be elastically stretchablein one or two directions. Further, the topsheet is fluid pervious,permitting fluids (e.g., urine, menses, other bodily fluids) to readilypenetrate through its thickness. A suitable topsheet can be manufacturedfrom a wide range of materials such as woven and nonwoven materials;apertured or hydroformed thermoplastic films; porous foams; reticulatedfoams; reticulated thermoplastic films; and thermoplastic scrims.Suitable woven and nonwoven materials may comprise of natural fiberssuch as wood or cotton fibers; synthetic fibers such as polyester,polypropylene, or polyethylene fibers; or combinations thereof.

Preferred topsheets for use in the present invention are selected fromhigh loft nonwoven topsheets and apertured film topsheet. Apertured filmtopsheet typically are pervious to bodily exudates, yet non-absorbent,and have a reduced tendency to allow fluids to pass back through andrewet the wearer's skin. Suitable apertured films include thosedescribed in U.S. Pat. No. 5,628,097, U.S. Pat. No. 5,916,661, EP1,051,958 (corresponding to U.S. Pat. No. 6,706,946), EP 1,076,539(corresponding to U.S. Pat. No. 6,545,197); the disclosure of each ishereby incorporated by reference.

Nonwoven materials, such as described in EP 774,242 (corresponding toU.S. Pat. No. 6,107,539) (Palumbo), which is incorporated herein byreference, generally exhibit high gas permeability, thus, do not exhibita significant resistance to air flow.

Further, suitable tospheet materials for depositing solid excretionsthereon may include nonwovens having apertures, which are at least inthe portions that are aligned with the feces deposition region of thearticle. Suitable apertured nonwovens are described in more detail in EP714,272 (corresponding to U.S. Pat. No. 6,414,215) or EP 702,543(corresponding to U.S. Pat. No. 5,342,338), and both of which areincorporated herein by reference. In another embodiment of feceshandling articles, such topsheets can be combined with feces handlingmembers e.g. underlying such topsheets, and further described in theseapplications.

The material forming the topsheet may be hydrophilic so as to facilitatefluid transport through the topsheet. Surfactants may be incorporatedinto the polymeric materials to improve the hydrophilicity of thetopsheet, such as is disclosed in EP-A-166,056 (corresponding to U.S.Pat. No. 4,647,448) and U.S. patent application Ser. No. 07/794,745,filed on Nov. 19, 1991, both of which are incorporated herein byreference. Alternatively, the topsheet may be treated with a surfactantto render the body-facing surface hydrophilic, such as is disclosed inU.S. Pat. No. 4,950,254, which is hereby incorporated by reference.

Absorbent Core

The absorbent core may include the following components: (a) optionally,a primary fluid distribution layer; (b) optionally, a secondary fluiddistribution layer; (c) a fluid storage layer; (d) other optionalcomponents, such as a fibrous “dusting” layer.

The optionally primary fluid distribution layer is typically disposedunder the topsheet and is in fluid communication with the topsheet. Thetopsheet transfers the acquired bodily fluids to the primarydistribution layer to ultimate distribution to the storage layer. Thistransfer of fluid through the primary distribution layer occurs not onlyin the thickness, but also along the length and width directions of theabsorbent core. The optionally secondary fluid distribution layer istypically disposed under the primary fluid distribution layer and is influid communication therewith. The secondary fluid distribution layerreadily acquires fluid from the primary distribution layer and transfersit rapidly to the underlying storage layer. Thus, the fluid capacity ofthe underlying storage layer may be fully utilized, especially whengushes of bodily discharge occur.

The fluid storage layer typically comprises absorbent materialsincluding absorbent gelling materials, which are usually referred to as“hydrogels”, “superabsorbent” “hydrocolloid” materials. Absorbentgelling materials are those materials that, upon contact with aqueousfluids, such as bodily fluids, imbibes such fluids and form hydrogels.These absorbent gelling materials are typically capable of absorbinglarge quantities of aqueous bodily fluids, and further capable ofretaining such absorbed fluids under moderate pressures. These absorbentgelling materials are typically in the form of discrete, nonfibrousparticles. Other forms, such are fibers, foams, sheets, strips, or othermacrostructures, are also suitable for use herein. Suitable absorbentgelling materials in the form of open cell foams may include thosedisclosed in U.S. Pat. No. 3,563,243 (Lindquist), U.S. Pat. No.4,554,297 (Dabi), U.S. Pat. No. 4,740,520 (Garvey), U.S. Pat. No.5,260,345 (DesMarais et al.), all of which are incorporated herein byreference. Improvements of these foams can be found in WO 96/21679(corresponding to U.S. Pat. No. 5,500,451), WO 96/21680 (correspondingto U.S. Pat. No. 5,650,222), WO 96/21681 (corresponding to U.S. Pat. No.5,563,179), WO 96/21682 (corresponding to U.S. Pat. No. 5,795,921), WO97/07832 (corresponding to U.S. Pat. No. 5,550,167) and WO 98/00085(corresponding to U.S. Pat. No. 5,873,869), all of which areincorporated herein by reference.

The absorbent gelling materials suitable for use herein may comprise asubstantially water-insoluble, slightly crosslinked, partiallyneutralized, polymeric gelling material. This material forms a hydrogelupon contact with water. Suitable absorbent gelling materials includethose disclosed in U.S. Pat. No. 4,654,039, U.S. Pat. No. 5,562,646,U.S. Pat. No. 5,599,335, U.S. Pat. No. 5,669,894, each of which isincorporated herein by reference.

The fluid storage layer may comprise absorbent gelling materials aloneor dispersed in a suitable carrier, homogeneously or inhomogenously, ormay comprise of absorbent carrier materials alone. The storage layer mayalso include filler materials, such as perlite, diatomaceous earth,vermiculite, and the like, which absorb and retain the fluid, and thus,reduce the rewet-through the topsheet.

Suitable carrier materials include cellulose fibers, in the form offluff, tissues or paper. Modified cellulose fibers (e.g., stiffened,chemically treated, crosslinked) may also be used. Synthetic fibers mayalso be used. Suitable synthetic fibers may be made of celluloseacetate, polyvinyl fluoride, polyvinylidene chloride, acrylics (such asOrlon®), polyvinyl acetate, non-soluble polyvinyl alcohol, polyethylene,polypropylene, polyamides (such as Nylon®), polyesters, bi- ortri-component fibers thereof, and mixtures of these materials.Preferably, the fiber surfaces are hydrophilic or are treated to behydrophilic.

Typically, the storage layer comprises from about 15 to 100 wt % of theabsorbent gelling material dispersed in a carrier material. Preferablythe storage layer comprises from about 30 to about 95 wt %, morepreferably from about 60 to about 90 wt % of the absorbent gellingmaterial. The carrier material typically comprises from about 0 to about85 wt %, preferably from about 5 to about 70 wt %, and more preferablyfrom about 10 to about 40 wt % of the storage layer.

An optional component for inclusion in the absorbent core is a fibrouslayer adjacent to, and typically underlying the storage layer. Thisunderlying fibrous layer is typically referred to as a “dusting” layersince it provides a substrate on which to deposit absorbent gellingmaterial in the storage layer during manufacture of the absorbent core.Further, the “dusting” layer provides some additional fluid handlingcapability such as rapid wicking of fluid along the length of theabsorbent core.

The absorbent core may include other optional components. For example, areinforcing scrim may be positioned within the respective zones, orbetween the respective zones, of the absorbent core. Optionally, odorcontrol agents may be included in the absorbent core. Suitable odorcontrol agents include active carbons, zeolites, clays, silicas, andmixtures thereof. The configuration and construction of the absorbentcore may also be varied (e.g., the absorbent core may have varyingcaliper zones, a hydrophilicity gradient, a pore size gradient, asuperabsorbent gradient, or lower average density and lower averagebasis weight acquisition zones; or may comprise one or more zones orstructures). The total absorbent capacity of the absorbent core should,however, be compatible with the designed loading and the intended use ofthe diaper. Further, the size and absorbent capacity of the absorbentcore may be varied to accommodate wearers ranging from infants throughadults. Suitable absorbent cores include those disclosed in EP 1,051,958(corresponding to U.S. Pat. No. 6,706,946), EP 797,968 (corresponding toU.S. Pat. No. 6,388,166) and EP 774,242 (corresponding to U.S. Pat. No.6,107,539), each of which is incorporated by reference herein.

Outer Cover

The term “outer cover” as used herein means a structural elementpositioned on the garment-facing surface of the absorbent article. Theouter cover typically forms the chassis onto which other components ofthe diaper are added. However, the outer cover may just be a coatinglayer on the garment side of the absorbent article.

Suitable material for the outer cover typically provide a barrierfunction with respect to liquids (i.e., liquid impervious) whilepreferably allowing air or vapor to flow through (i.e., vaporpermeable). Typically, the outer cover is not the rate limiting elementto gas or vapor transport through the absorbent article. In someembodiments, the outer cover may have a structure that is relativelyopen to allow for convective air or gas permeability. The suitable outercover typically has a moisture vapor transmission rate (MVTR) of atleast about 500 g/m²/24 hrs, more preferably of at least about 1500g/m²/24 hrs, and most preferably at least about 3000 g/m²/24 hrs.Additionally, the outer cover provides a soft, pleasant feel to theskin, either by the material property, or by texturizing or embossingits surface, or both.

The outer cover may be a single layer of homogeneous or multi-componentmaterial, or a composite of various layers of materials. The outer coversuitable for use herein comprises porous materials such as an aperturedfilm (e.g., having a plurality of shaped openings or angledcapillaries), a knitted web, a porous woven or nonwoven web, a foam, orcombinations or laminates thereof. In one embodiment, the outer covercomprises nonwoven webs or multi-layered nonwovens such asspunbond/meltblown (SB) nonwoven, spunbond/meltblown/spunbond (SBS)nonwoven.

The outer cover, or any portion thereof, may be elastically extensiblein one or more directions. In one embodiment, the outer cover maycomprise a structural elastic-like film (“SELF”) web. A SELF web is anextensible material that exhibits an elastic-like behavior in thedirection of elongation without the use of added elastic materials andis described in more detail in U.S. Pat. No. 5,518,801 entitled “WebMaterials Exhibiting Elastic-Like Behavior” issued to Chappell, et al.on May 21, 1996, which is incorporated herein by reference. In alternateembodiments, the outer cover may combine elastomeric components (such asfilms, foams, strands, or combinations thereof) with nonwovens orsynthetic films.

In another embodiment, the outer cover may be a nonwoven web constructedto provide the required level of liquid impermeability. For example, anonwoven web of spunbonded or meltblown polymer fibers may be treated,at least partially, with a hydrophobic coating. Exemplary treatmentsusing fluorocarbons are described in U.S. Pat. No. 5,876,753, issued toTimmons et al. on Mar. 2, 1999; U.S. Pat. No. 5,888,591 issued toGleason et al. on Mar. 30, 1999; U.S. Pat. No. 6,045,877 issued toGleason et al. on Apr. 4, 2000; U.S. Patent Application Ser. No.99/20504 by D'Agostino et al., filed on Mar. 7, 1999; the disclosures ofwhich are hereby incorporated by reference.

Optionally, the outer cover material may comprise the absorbent andswellable materials described in U.S. Pat. No. 5,955,187 issued toMcCormack et al. on Sep. 21, 1999; or the absorbent and shrinkablematerials described in U.S. Patent Application Serial no. 97/22604 byCorzani et al. on Dec. 15, 1997; or the absorbent and differentialstrainable materials described in PCT Publication WO 00/68003 by Dawsonet al. (corresponding to U.S. Pat. No. 6,770,579); the disclosures ofwhich are hereby incorporated by reference.

The absorbent article may comprise an outer cover which is separatedfrom the absorbent core at least partially by the absorbent barrierstructure of the present invention and is preferably joined to theabsorbent barrier structure and/or the absorbent core by attachmentmeans such as those well known in the art.

The outer cover may be secured to the absorbent barrier structure and/orthe absorbent core by a uniform continuous layer of adhesive, an openpattern network of filaments of adhesive, or an array of separate lines,spirals, or spots of adhesive, as disclosed in U.S. Pat. No. 4,573,986issued to Minetola et al. on Mar. 4, 1986; U.S. Pat. No. 3,911,173issued to Sprague, Jr. on Oct. 7, 1975; U.S. Pat. No. 4,785,996 issuedto Ziecker, et al. on Nov. 22, 1978; and U.S. Pat. No. 4,842,666 issuedto Werenicz on Jun. 27, 1989; the disclosure of each is incorporatedherein by reference. Adhesives suitable for use herein are manufacturedby H.B. Fuller Company of St. Paul, Minn. and marketed as HL-1258.Alternatively, the attachment means may comprise heat bonds, pressurebonds, ultrasonic bonds, dynamic mechanical bonds, or any other suitableattachment means or combinations of these attachment means as are knownin the art.

The outer cover material may not significantly lower the convective airpermeability of the absorbent article. More importantly, the combinationof the absorbent barrier structure and the outer cover (hereinafterreferred to as the “combined structure” or “combination”) provide thedesired balance of properties, including, but not limited to,absorbency, barrier property and convective air permeability.

The combined structure of the present invention may be constructed tohave a convective air permeability of at least about 10 Darcy/mm,preferably at least about 20 Darcy/mm, more preferably at least about 30Darcy/mm, and most preferably at least about 50 Darcy/mm. Convective airpermeability is especially effective in removing moisture vapor frominside the absorbent article, resulting in a lower humidity in the localenvironment next to the skin, which reduces incidences of skinirritation or rash and promotes skin health.

Further, the combined structure of the present invention preferably hasa liquid impact transmission value (as measured by Test Method C) of nomore than about 10 g/m², more preferably no more than about 8 g/m², andmost preferably no more than about 5 g/m².

Moreover, the combined structure should exhibit a hydrohead value of atleast about 20 mBars, preferably at least about 35 mBars, morepreferably at least about 50 mBars, and most preferably at least about75 mBars.

In a preferred embodiment, the combined structure of the presentinvention exhibits desired leakage protection or barrier properties atleast equal to that of the absorbent barrier structure.

Dampness Management Means

Optionally, as shown in FIG. 1, a dampness management means 26 may beincluded in the absorbent article of the present invention. The dampnessmanagement means 26 may provide further leakage protection. Suitablematerials for dampness management means 26 are breathable materialswhich permit vapors to escape from the diaper 20. Exemplary materialsmay include apertured films; monolithic or microporous films, preferablywith apertures; modified (with respect to pore structures anddistributions) nonwovens or composite materials such as film/nonwovenlaminates.

Suitable apertured films typically have open surface area at least about1%, preferably at least about 5% more preferably at least about 10%. Inanother embodiment, the open surface area may be 0.1% or more, providedthere are sufficient amount of relatively large pores present. Further,suitable apertured films should have an open surface area less thanabout 20% such that it would have insubstantial effect on the leakageprotection properties of the article. Apertured films may be vacuumformed or hydro-formed to provide macro and/or micro apertures. Moredetailed descriptions of suitable apertured films can be found in U.S.Pat. No. 4,629,643, U.S. Pat. No. 4,609,518 and U.S. Pat. No. 4,695,422,U.S. Pat. No. 4,342,314 and U.S. Pat. No. 4,463,045; the disclosure ofeach is incorporated by reference herein.

In another embodiment, the dampness management means may include zonesof different breathability and/or liquid permeability. For example, thedampness management means may be higher in breathability and/or liquidpermeability in zones which do not coincide with the absorbent core. Asused herein, the term “breathability” refers to the diffusive transportof water vapor through the material. The dampness management means maybe assembled of one or more layers and preferably includes at least onelayer which is liquid impermeable, the liquid impermeable layerpreferably located adjacent the absorbent core and preferably covers anarea at least as large as the absorbent core.

Further, moisture condensation on the outer surface (i.e., the garmentside) of the absorbent article leads to dampness to the touch, whichreduces wearer comfort and is often perceived as a performance problemwith the article. The convective transport of moisture vapor through theabsorbent article of the present invention is very effective such thatit may lead to moisture condensation on the outer surface of the articleand the perceived dampness problem. Thus, it may be beneficial toincorporate a relatively low breathability dampness management meansinto the article of the present invention. Suitable low breathabilitydampness management means should have a MVTR of no more than about 4500g/m²/24 hrs, preferably of no more than about 3500 g/m²/24 hrs, morepreferably no more than about 3000 g/m²/24 hrs, and most preferably nomore than about 2500 g/m²/24 hrs.

The dampness management means may be disposed between the outer coverand the absorbent barrier structure of the present invention.Alternatively, the dampness management means may be disposed within theabsorbent barrier structure between the absorbent layer and one or bothof the barrier layers.

Other Components

In addition, the diaper, as represented in FIG. 3, may further include apair of fasteners 40 which are employed to secure the diaper about thewaist of the wearer. Suitable fasteners include hook-and-loop typefasteners, adhesive tape fasteners, buttons, snaps, mushroom-and-loopfasteners and the like. The diaper of the present invention may alsoinclude elasticized leg bands which help secure the diaper to the wearerand, thus, help reduce leakage from the diaper. Similarly, it is alsoknown to include a pair of elasticized, longitudinally extendingcontainment flaps which are configured to maintain a substantiallyupright, perpendicular arrangement along the central portion of thediaper to serve as an additional barrier to the lateral flow of bodyexudates.

It is also common to include a surge management layer positioned betweenthe topsheet and the absorbent core in order to help prevent pooling offluids on the portion of the diaper adjacent the wearer's skin.

The articles of the present invention may also include waste managementfeatures, such as pockets for receiving and containing waste, spacerswhich provide voids for waste, barriers for limiting the movement ofwaste in the article, compartments or voids which accept and containwaste materials deposited in the diaper 20, and any combinationsthereof.

Optionally, the absorbent articles of the present invention may includea skin care composition, preferably on the skin-contacting surfaces ofthe article. The skin care composition useful herein is directed tomaintain and/or improve the skin condition of the skin under anabsorbent article or skin that is subjected to chronic or acuteexposures to body exudates, moisture, irritants, etc. It is preferredthat the skin care composition provides a protective, and preferablynon-occlusive function (e.g., a relatively liquid impervious but vaporpervious barrier) to avoid skin overhydration and skin exposure tomaterials contained in body exudates (e.g., urine, feces, menstrualfluids). It is also preferable that the skin care composition providesan abrasion minimizing function to reduce skin irritation in the areaswhere the absorbent article is in contact with the wearer's skin.Additionally, the skin care composition may contain skin careingredients, which directly or indirectly, deliver skin care benefits,such as reduction of overhydration, reduction of redness, skinconditioning, and removal or reduction of skin irritants in bodyexudates. It is also preferred that the skin care composition containsemollients that protect or improve the skin against chaffing, roughness,wrinkled appearance or itchiness. The skin care composition may alsocontain skin soothing agents, such as aloe vera, and chamomile.

Skin care compositions suitable for use in the present invention aredescribed in U.S. patent application Ser. Nos. 08/926,532 and08/926,533, each filed on Sep. 10, 1997; U.S. patent application Ser.Nos. 09/041,509, 09/041,232 and 09/041,266, each filed on Mar. 12, 1998;U.S. patent application Ser. No. 09/563,638, filed on May 2, 2000; U.S.Pat. No. 5,607,760 issued Mar. 4, 1997; U.S. patent application Ser. No.09/466,343, filed on Dec. 17, 1999; U.S. Pat. No. 5,609,587 issued Mar.11, 1997; U.S. Pat. No. 5,635,191 issued Jun. 3, 1997; U.S. Pat. No.5,643,588 issued Jul. 1, 1997; and U.S. Pat. No. 6,153,209 issued Nov.28, 2000; the disclosures of which are hereby incorporated by reference.

Making the Absorbent Barrier Structure

In one embodiment, the nonwoven web and the cellulosic web forming theabsorbent barrier structure are adhesively bonded together usingAto-Findley adhesive H2031F. The nonwoven web is unwound from a supplyroll and advances to the spray station where the adhesive is pre-heatedto its melt state and sprayed (using a DYNATEC® spray head) onto the websubstrate before the nonwoven web is assembled with the cellulosic webto form the absorbent barrier structure. The adhesive forms threecontinuous stripes along the longitudinal direction of the advancingweb. The stripes are substantially parallel. Each stripe is 22 mm inwidth and the outer stripes are about 4 mm from the peripheries of theweb.

In another embodiment, the first nonwoven web and the cellulosic web maybe adhesively joined together according to the method described above. Asecond nonwoven web is unwound from a supply roll, spray-coated withadhesives, then joined to the free surface of the cellulosic web. Inanother three-layered absorbent barrier structure, the two nonwoven websmay be unwound from separate supply rolls and spray-coated withadhesives, then simultaneously joined to the opposed surfaces of thecellulosic web.

The absorbent barrier structure may be incorporated into a disposablediaper having the general construction as the diaper shown in FIG. 1following well-known assembly processes. Typically, the absorbentbarrier structure is disposed between the absorbent core and the outercover. In a two-layered construction, the barrier layer is disposedadjacent to the garment-facing side of the absorbent core and theabsorbent layer is disposed adjacent to the outer cover. In athree-layered construction, the first barrier layer is disposed adjacentto the garment-facing side of the absorbent core and the second barrierlayer is disposed adjacent to the outer cover. Other well knowncomponents may be incorporated within the diaper without departing fromthe spirit of the present invention. Further, the manner and method ofusing these well known components in connection with the absorbentarticle of the present invention will likewise be readily appreciated bythose skilled in the art.

Test Methods

A. Air Permeability

The air permeability is determined by measuring the time in which astandard volume of air is drawn through the test specimen at a constantpressure. This test is particularly suited to materials havingrelatively high permeability to gases, such as nonwovens, aperturedfilms and the like.

A TexTest FX3300 instrument (available from Advanced TestingInstruments, Corp., Spartanburg, S.C.) is used. The Test Method conformsto ASTM D737. The test is operated in a laboratory environment typicallyabout 22±2° C. and about 35±15% relative humidity. The test specimen iskept in this laboratory environment for at least 2 hours prior totesting. The test pressure is 125 Pascals and the test area is 38 cm².In this test, the instrument creates a constant differential pressureacross the sample which draws air through the sample. The rate of airflow through the sample is measured in ft³ per min per ft² (ft³/min/ft²)and converted to permeance (in Darcy/mm) according to the Darcy's Law:K/d(Darcy/mm)=(V·μ)/(t·A·Δp)wherein K is the permeability per unit area of the specimen; V/t is thevolumetric flow rate in cm³/sec; μ is the viscosity of air (1.86·10⁻⁵ Pasec); d is the test material thickness in mm; A is the cross sectionalarea of the specimen in cm²; Δp is the pressure differential in Pascalor Pa; and 1 Darcy=9.869·10⁻⁹ cm².

For each sample, three replicates should be run, and the averaged resultis reported.

B. Hydrostatic Head (Hydrohead) Pressure Test

This property determined by this test is a measure of the liquid barrierproperty (or liquid impermeability) of a material. Specifically, thistest measures the hydrostatic pressure supported by the material at thepoint when water penetration through the material first occurs.

A TexTest Hydrostatic Head Tester FX3000 (available from AdvancedTesting Instruments, Corp., Spartanburg, S.C.) is used. The test methodconforms to Edana 120.1-18. For this test, pressure is applied to adefined sample portion and gradually increases until water penetratesthrough the sample.

The test is conducted in a laboratory environment typically about (22±2°C.) and a relative humidity of about 35±15%. The test specimen is keptin this laboratory environment for at least 2 hours prior to testing.The sample is clamped over the top of the water reservoir of theinstrument, using gasketing material to prevent side leakage duringtesting. When testing an absorbent barrier structure of the presentinvention, which comprises a layer of a barrier material and a layer ofa reservoir material, the sample is oriented such that the layer of thebarrier material faces the water during the test. The area of watercontact with the sample is 28 cm².

The water pressure is increased at a rate of 3 mBar/min. Thus, thesample is subjected to a steadily increasing water pressure on thesurface of the barrier layer. When water breakout appears on threelocations on the top surface of the sample, the pressure at which thethird breakout occurs is recorded. For some samples, the water breakoutsat various locations may occur contemporaneously, the pressure at theinstant the breakouts occur is recorded. If water immediately penetratesthe sample (i.e., the sample provided no resistance), a zero reading isrecorded. For each material, three specimens are tested and the resultsare averaged.

C. Liquid Impact Transmission Test

The properties determined by this method correlate with the fluidresistance capability under sudden impact, which relates to leakageprotection, provided by the absorbent structure of the presentinvention. In this test, a sample of the absorbent structure is layeredwith a loaded absorbent core simulant, and the combination is subjectedto an impact force. The properties determined by this method is relevantto the actual use condition where the wearer (especially a baby) fallingfrom a standing position, thus, applying an impact force on a loadeddiaper.

Liquid impact transmission test is measured with the apparatus 9100shown in FIGS. 5A and 5B. The receiving table 9120 is supported by fouradjustable legs, which level the receiving table 9120. The impactassembly includes a head 9107 and an arm 9110. The head 9107 includes ahammer 9108 (a metal cylinder of 63 mm in diameter) mounted on a baseplate 9109. The arm 9110 is attached to the base plate 9109 on one endand is pivotally attached to hinge 9118 on the other end. The lengthfrom hinge 9118 to the distal end of the base plate 9109 is about 551mm. The arm 9110 is attached to a mounting piece 9114 by a release pin9112. The mounting piece 9114 is positioned (by knob 9116) at a desired(typically 30°) angle with respect to the horizontal table 9120.

An energy absorbing impact pad 9205 is 12.7 cm by 12.7 cm (5 inches by 5inches) and 0.79 cm (0.3125 inches) thick. The energy absorbing impactpad 9205 is made of silicone rubber sheeting (Part no. 8632 K37,available from McMaster Carr of Cleveland, Ohio). The energy absorbingimpact pad 9205 is attached to a metal plate 9206 of the same dimension.The metal plate 9206 is supported by a shock absorber 9207 (Model MA 600from Ace Controls, Inc., Farmington, Mich.). The bottom surface of themetal plate 9206 is about 10 mm above the receiving table 9120 in thestarting position (FIG. 5A). The adjustment knob 9208 of the shockabsorber 9207 is set (at about 5) to smooth the deceleration throughoutthe stroke. When properly set-up, the hammer 9108 renders a dead blow(i.e., no observable rebound) on the sample assembly.

An absorbent core simulant 9204 is placed is centrally placed on top ofthe energy absorbing impact pad 9205. The absorbent core simulant 9204comprises four layers of No. 4 filter paper (70 mm diameter) availablefrom Whatman Laboratory Division, Distributed by VWR Scientific ofCleveland, Ohio. The core simulant 9204 is evenly loaded with 2 grams ofsimulated urine. The simulated urine is an aqueous 0.9% by weight salinesolution, exhibiting a surface energy value of 72.5 mN/m asconventionally determined.

Sample 9203 is a barrier absorbent structure of the present inventionthat includes a barrier zone and a reservoir zone arranged in layers.Sample 9203 is centrally placed over the core simulant 9204, with thebarrier layer facing the core simulant 9204. The surface area of thecore simulant 9204 and sample 9203 are slightly larger than the surfacearea of block 9108, which is 63 mm in diameter (0.003117 m² in area).

An absorbent material 9202 is weighed to the nearest 0.0001 gram andplaced on top of sample 9203 to absorb and retain simulated urine, whichpasses through sample 9203. The absorbent material 9202 comprises a No.4 filter paper (70 mm diameter) available from Whatman LaboratoryDivision.

A weight 9201 is centrally placed on top of absorbent material 9202 toweigh down the sample assembly. The weight 9201 is made of Plexiglas,measures 5″ by 5″ (12.7 cm by 12.7 cm) and weighs about 206 gm. Theweight 9201 has a circular hole in the center whose diameter (75 mm) isslightly larger than the diameter of the hammer 9108. When arm 9110 isreleased, hammer 9108 strikes through the central hole in weight 9201and renders a dead blow on the central portion of the sample assembly.

In the pre-test position (FIG. 5A), the arm assembly is held at the sameangle as the mounting piece 9114 by release pin 9112. To initiate theimpact test, the release pin 9112 is pulled, whereby arm 9110 changesfrom a starting position, as shown in FIG. 5A, to a horizontal finalposition, as shown in FIG. 5B. A stop watch is activated upon impact totime the experiment.

In the particular set-up described above, hammer 9108 reaches anacceleration of 70 times gravity when the metal plate 9206 touches thereceiving table, thereby initiating the deceleration. Thus, the impactassembly applies an impact force of 2060 Newtons (according to theformula: force=weight*acceleration) on the sample assembly. Anaccelerometer (model 353B02, available from PCB Piezotronics, Inc.Depew, N.Y.) may be used to measure the acceleration. To obtain theweight, the release pin 9112 is pulled to free the impact assembly fromthe mounting piece 9114; then, the receiving table 9120 is tilted to theposition that places arm 9110 in a horizontal position and hammer 9108resting on a top-loading balance. The weight registered on the balanceis used in the formula above. For the particular set up used herein, theweight is about 3 kg. The weight and length of the impact assembly aswell as the angle of the mounting piece 9114 may be different from thosespecified above, so long as these elements together provide an impactforce of 2060 Newtons upon impact.

The impact assembly is then allowed to rest in this horizontal positionfor two minutes. The arm 9110 is raised and the filter paper 9202 isremoved and placed on a balance. The weight of the filter paper 9202 atthree-minutes from impact is recorded. The Liquid Impact Transmission(LIT) value is calculated and expressed in grams/m² using the followingformula:LIT=[final weight of the filter paper−initial weight of the filterpaper]/[impact area]wherein the impact area, expressed in m², is the area of the coresimulant 9204 (about 0.003848 m²). For each material, three specimensare tested and the averaged result is reported.D. Static Liquid Transmission Test

The property determined by this test correlates with the fluid retainingability (or leakage protection) provided by the absorbent barrierstructure of the present invention under an impact and sustainedpressure condition. The property determined by this test is relevant tothe actual use condition where the wearer suddenly moves from a standingposition to a second position (e.g., sitting), and maintains the secondposition for an extended time period.

The equipment and sample set-up are the same as those described above inthe Liquid Impact Transmission Test, except in this test, arm 9110 isdropped to deliver an impact force of 2060 Newtons and is allowed torest on the sample for a set period of time (the “hold time”). Arm 9110is then raised, the filter paper 9202 is removed and weighed, and thechange in weight is reported as described above. The hold times at thehorizontal resting position are 2, 5, 8, 15, 30 and 60 minutes.

E. Moisture Vapor Transmission Rate

The Moisture Vapor Transmission Rate (MVTR) determines the amount ofmoisture adsorbed by calcium chloride in a “cup” like container that iscovered by a test specimen. The moisture source is a controlledtemperature and humidity environment (40±3° C. and 75±3% relativehumidity) separated from the calcium chloride by the test specimen. Thismethod is applicable to test specimens such as thin films, multi layerlaminates and the like.

The sample holding cup is a cylinder with an inner diameter of 30 mm andan inside height from bottom to top flange of 49 mm. A flange having acircular opening to match the opening of the cylinder can be fixed byscrews, and a silicone rubber sealing ring with an opening matching theinner diameter of the cup fits between the top flange and the cylinder.The test specimen is positioned such that it covers the cylinderopening. The specimen is securely fixed between the silicone rubbersealing and the upper flange of the cylinder so it acts as a barrier tomoisture transport.

The equipment as well as the test specimen should be equilibrated (abouttwo hours or more) to the temperature of the controlled environmentprior to testing.

The absorbent desiccant material is CaCl₂, such as can be purchased fromWako Pure Chemical Industries Ltd., Richmond, Va. under the productdesignation 030-00525. If kept in a sealed bottle, it may be useddirectly. It may be sieved to remove lumps or fines, if existing. It mayalso be dried at 200° C. for about 4 hours prior to use.

The CaCl₂ is poured into the cup. The cup is tamped down 10 times. Thena spacer is used to set a 1 cm gap between the top of the CaCl₂ and thetop of the cup.

A test sample, cut to about 3.2 cm by 6.25 cm, is placed flat andoverlapping the opening of the cup. The silicone rubber seal and theflange are placed on top of the sample and aligned with the screw holesand are affixed by the screws without over tightening. The total weightof the cup assembly is accurately recorded to three decimal places, andthe assembly is placed into the constant temperature/humidity chamber.

After 5 hours exposure to the test humidity (without opening ofchamber), the sample is removed and immediately covered tightly with anon-vapor permeable plastic film such as SARAN WRAP. After cooling about30 minutes to allow for temperature equilibration, the plastic film isremoved and the assembly is reweighed.

The MVTR value is then calculated by determining the moisture increaseover 5 hours due to transport through the 3 cm circular opening andconverting the result to units of grams per meter square per 24 hours(g/m²/24 hr). For each sample, three replicates should be run, theresulting values will be averaged, and the result rounded to the nearest100 value.

F. Post-Compression Air Permeability

When a material, especially one with a relatively flexible or openstructure, is subjected to compaction or sustained pressure, thematerial may experience structural changes. After the applied forces areremoved, the material may not return to its original state completely.This residual structure change often results in changes in properties,such as air permeability. This test method is a measure of theresilience of the sample material after it has been subjected tocompaction or a sustained pressure for a pre-determined period of time.

When an absorbent barrier structure of the present invention isincorporated into absorbent articles, such as diapers, the articles areoften packaged in a highly compact condition, and stored under suchcondition for an extended period of time. Moreover, while the absorbentarticle is worn, the wearer may subject the article to sudden impactforce (e.g., the wearer moves from a standing to a sitting positionabruptly), which may be followed by a sustained pressure (e.g., thewearer maintains the sitting position). Certain materials or structuresare susceptible to change under such conditions, and do not recover totheir original state even after the compaction or pressure has beenremoved. Thus, a material or structure may have high air permeabilitywhen made, but may not be able to deliver such performance after it hasbeen compacted and stored in a package or when it suffers sustainedpressure applied by a wearer.

Samples (typically, multi-layered laminates) are cut to 40 mm by 165 mmin size. The samples are stacked and placed between two Plexiglasplates. Weight is applied over the Plexiglas plates, resulting in apressure of 50 g/cm² (0.7 psi), thereby the overall caliper of the stackof sample sheets is reduced. The level of compression is calculatedaccording to the following:H=k×n×dwherein

-   -   H is the overall caliper after pressure is applied to compress        the sample stack;    -   d is the initial caliper of a sample sheet;    -   n is the number of sample sheets; and    -   k is the compression level.

The compressed sample stacks are placed inside a climate-controlledchamber at 60° C., 50% relative humidity, for a pre-determined timeperiod. Typically, the test is done with five samples in each stack andat 50% compression.

Air permeability of the sample is determined before compression andafter 24 hours in compression. The post compression air permeability ismeasured after a waiting period, which is sufficient to allow the sampleto recover (taking into consideration that the sample may exhibitpermanent deformation and will not recover to its original,pre-compression state). For this test, the air permeability isdetermined by measuring the time in which a standard volume of air isdrawn through the test specimen at a constant pressure and temperature.

The samples (e.g., the absorbent barrier structure prepared with pre- orpost-compression sheets) are conditioned in a temperature and humiditycontrolled environment, at 22±2° C. and 35±15% relative humidity for atleast 2 hours before testing.

The test equipment as manufactured by Hoppe & Schneider GmbH,Heidelberg, Germany, under the designation “Textiluhr nach Kretschmar”,is essentially a bellows in a vertical arrangement, with its upper endbeing mounted in a fixed position, and the lower end being releasablyheld at its upper position, which can be loosened by means of a releasehandle to slide under controlled conditions to the lower position,thereby increasing the volume inside the bellows by pulling air throughthe test specimen which is covering the air entering opening at theupper end of the bellows. The test specimen is firmly held to cover theair entering opening by means of a fastening ring of 5 cm² or 10 cm² toallow for different samples sizes and/or different permeability ranges.If the 10 cm² ring is used, (he sample should be at least 55 mm wide,for the 5 cm² ring at least 35 mm. For both, the samples should have alength of about 150 mm.

In case of very high permeability materials, the opening can he furtherreduced, with appropriate adjustments to the equipment and calculation.

The equipment comprises a stopwatch ( 1/100 sec) which automaticallymeasures the time between the operation of the release handle whichstarts the sliding of the bellows, and the stop of the bellows whentheir bottoms reach the lower end.

The air permeability k of the material is calculated by the Darcy law asdescribed above, wherein different parameters are used (due to thedifferences in equipment set-up). Specifically for the test equipmentused here, V is 1900 cm³, A is 4.155 cm² and Δp is 160 Pa.

The test is repeated once for each test sample (either sheets made ofsingle material or laminates of different materials), and should berepeated on five samples. For each sample material or laminate, heaverage of at least three satisfactory runs is reported. The averagedvalue is reported in Darcy/mm, taking into account the unit thickness ofthe material.

G. Absorption Test

This test measures the high suction capillary absorption of absorbentmaterials. Capillary sorption is a fundamental property of any absorbentthat governs how fluid would be absorbed by the absorbent structure.High suction capillary sorption characterizes the ability of a materialto partition fluid from competing materials.

A porous glass frit is connected via an uninterrupted column of fluid toa fluid reservoir whose fluid level is located at the same height as thehorizontal center of the frit porous structure. The sample absorbs fluidupon demand and its weight at equilibrium is recorded. The fixed heightcapsorption experiment thus gives information about the liquid uptake(g/g) in the horizontal direction.

Experimental Setup

The test liquid used herein is 0.2 wt % TRITON® X-100 (available fromSigma-Aldrich Inc.) aqueous solution having a surface tension of about33 dyne/cm). This test method may be adapted to use other test liquidssuch as water or synthetic urine (having a surface tension of about 75dyne/cm and about 55 dyne/cm. respectively).

A porous glass fritted funnel is filled with the test liquid. Thefritted funnel (available from VWR Scientific Products, Cleveland, Ohio)has a 350 ml volume and 10.15 micron pores its bottom outlet is modifiedby glass blower to accommodate tubing. The fritted funnel is invertedsuch Chat the funnel opening is resting on a flat surface and the bottomoutlet is facing up. A 1.40 in long piece of Tygon tubing (Part No.R3603, available from VWR Scientific Products) is attached to the funnelbottom and filled with test liquid. The fritted funnel is then turneduptight and clamped unto a stand. The Tygon Cubing end is secured to thefritted funnel with the tubing end raised several centimeters above thefritted disk.

The funnel is filled with 100 ml of test liquid (the raised tubing endprevents the liquid from draining through the frit) and covered withplastic wrap. The frit is then stored for 5–12 hours to allow any airtrapped in the frit pores to escape. Any observable air bubbles shouldalso be removed from the frit or the tubing. For testing, the Tygontubing is placed in the glass fluid reservoir (20–25 cm diameter) filledwith test liquid. The center of the frit and the fluid level in thereservoir are set to the same height. A level is used to ensure that thefrit surface is horizontal. In between experiments the fritted funnel iscovered with plastic wrap to prevent evaporation and drying of the testliquid in the frit pores; however, during an experiment the frittedfunnel is not covered. If frits are not used for several hours, theyshould be stored as follows: the Tygon tubing is removed from the fluidreservoir and secured to the fritted funnel with the tubing end raisedseveral centimeters above the fritted disk. The funnel is filled with100 ml of test liquid (the raised tubing end prevents the liquid fromdraining through the frit) and covered with plastic wrap.

Experimental Procedure

Ensure that no observable air bubbles are trapped below the frit or inthe tubing. Cut a 5.40 cm diameter sample using an arch punch. Weigh thesample. Clamp off tubing below fritted funnel. Place the pup cylinderonto the frit surface centered. Place the sample into the pup cylinder,making sure that it is centered and lying flat on the frit surface.Gently insert the pup piston into the pup cylinder over the sample.Place a ring weight on the pup cylinder. Remove the clamp and allow thesamples to absorb for 2.5 minutes. Remove the ring weight, the puppiston, the pup cylinder and then the sample from frit. If it isnecessary to lower the fritted funnel or tilt it for sample removal, thefritted funnel tubing has to be clamped off below the fritted funnelprior to removing the sample from the frit (to ensure that no additionalfluid is absorbed by the sample during removal). Weigh the sample.Repeat procedure with the next sample. Perform two replicates for eachsample and report the net uptake obtained for each sample as well as theaverage net uptake. Report which frits were used (frit number or otheridentification). If results of the two tests differ by more than 10%(based on the higher value), check frits and sample preparation andrepeat the experiment. The liquid absorption (or uptake) by the sampleis calculated according to the following: Net uptake, g/g=(sample wetweight, g−sample dry weight, g)/sample dry weight, g

EXAMPLES Example 1

In this example, the absorbent barrier structure of the presentinvention is a two-layered laminate comprising an absorbent zone and abarrier zone substantially superimposed over the barrier zone. FIG. 2Aillustrates this embodiment schematically, wherein the absorbent barrierstructure 10 includes a barrier layer 12 and an absorbent layer 14. Theabsorbent layer is a natural fiber cellulosic web commercially availableas BOUNTY® paper towel (manufactured by the Procter and Gamble Company,Cincinnati, Ohio). BOUNTY® has a two-ply construction, with a totalbasis weight of about 43 gsm and a total thickness of about 0.686 mm.The barrier layer is a polypropylene spunbond/meltblown nonwoven web(manufactured by BBA Nonwovens, Simpsonville, S.C. under the designationMD2005) which has a basis weight of about 27 gsm and a thickness ofabout 0.305 mm.

Example 2

In this example, the absorbent barrier structure has a three-layeredstructure, which includes a first and a second barrier zones aredisposed on the opposed sides of the absorbent zone. FIG. 2B illustratesthis embodiment schematically, wherein the absorbent barrier structure10 includes two barrier layers 12 and 16 and an absorbent layer 14between the two barrier layers. The absorbent layer is a two-ply BOUNTY®paper towel. The first and the second barrier layers are meltblownpolypropylene nonwoven webs (manufactured by Jentex Corporation, Buford,Ga. with the designation PP-015-F-N, X2009A). Each of the MB nonwovenweb has a basis weight of about 15 gsm.

Example 3

In this example, the absorbent barrier structure has substantially thesame construction as described in Example 2, except that the firstbarrier layer is a MB polypropylene nonwoven web from Jentex(PP-010-F-N, X2009A) with a basis weight of about 10 gsm. The secondbarrier layer is a spunbond/spunbond polypropylene nonwoven web made ofmicrodenier fibers with a basis weight of about 17 gsm (available fromFirst Quality Fibers Nonwovens, Hazelton, Pa. under the designation GCAS16002184).

Example 4

In this example, the absorbent barrier structure has substantially thesame construction as described in Example 2, except that the firstbarrier layer is a MB nonwoven web from Jentex (PP-005-F-N, X2009A) witha basis weight of about 5 gsm and the second barrier layer is a MBnonwoven web from Jentex (PP-010-F-N, X2009A) with a basis weight ofabout 10 gsm.

Example 5

In this example, the absorbent barrier structure has substantially thesame construction as described in Example 2, except that the firstbarrier layer is a MB nonwoven web from Jentex (PP-010-F-N, X2009A) witha basis weight of about 10 gsm and the second barrier layer is a MBnonwoven web from Jentex (PP-005-F-N, X2009A) with a basis weight ofabout 5 gsm.

Example 6

In this example, the absorbent barrier structure has substantially thesame construction as described in Example 2, except that the absorbentlayer is a single-ply BOUNTY® paper towel.

Example 7

In this example, the absorbent barrier structure has substantially thesame construction as described in Example 3, except that the absorbentlayer is a single-ply BOUNTY® paper towel.

Example 8

In this example, the absorbent barrier structure has substantially thesame construction as described in Example 2, except that the absorbentlayer comprises two superimposed layers of single-ply BOUNTY® papertowel.

The properties of the above examples are tested according to the TestMethods disclosed herein. For the three-layered structure, the firstbarrier layer is disposed adjacent to the absorbent core during thetests. The results are summarized in Table 1 below. The test results inTable 1 indicate that the present invention provides a unique structurehaving the desirable balance of properties.

TABLE 1 LIQUID IMPACT AIR TRANS- PERME- HYDROHEAD MISSION BASIS ABILITYPRESSURE VALUE WEIGHT EXAMPLE (Darcy/mm) (mBars) (gsm) (gsm) 1 57 41.37.2 70 2 24 49.3 6.8 73 3 51 45.3 8.3 69.3 4 47 23.5 7.4 57.1 5 46 39.38.5 57.1 6 24 55.5 10.5  54 7 59 33.7 13.2  51 8 21.4 81.5 7.1 78

Comparative Examples

Comparative Example 1 is a two-ply BOUNTY® paper towel.

Comparative example 2 is a formed film having angled capillaries on itssurface such as those described in EP 934,735 and EP 934,736. The formedfilm is made of polyethylene and is available from Tredegar FilmProducts Corporation, Terre Haute, Ind.

Comparative example 3 is a microporous film. The microporous film ismade of polyethylene having 40–45 wt % CaCO3 fillers. The microporousfilm is available from Clopay Plastic Products Company, Cincinnati,Ohio.

Comparative example 4 is a polypropylene SS nonwoven web available fromFirst Quality Fibers Nonwovens, Hazelton, Pa. under the designation GCAS16002184.

Comparative Example 5 is a polypropylene MB nonwoven web available fromJentex Corporation, Buford, Ga.) with the designation PP-015-F-N,X2009A.

The properties of the comparative examples are tested according to theTest Methods disclosed herein. For the three-layered structure, thefirst barrier layer is disposed adjacent to the absorbent core duringthe test results are summarized in Table 2 below.

TABLE 2 LIQUID IMPACT AIR TRANS- COMPAR- PERME- HYDROHEAD MISSION BASISATIVE ABILITY PRESSURE VALUE WEIGHT EXAMPLE (Darcy/mm) (mBars) (gsm)(gsm) 1 143 <0.5 57 43 2 133 3 5 42 3 0.05 >100 0.2 52 4 407 10.8 37 175 53 68.5 25 15

The test results in Table 2 indicate that the comparative examples failto provide the desirable balance of properties. BOUNTY® paper towel(Comparative example 1) has excellent air permeability but poor liquidimpermeability. Microporous film (Comparative example 2) has excellentliquid impermeability but is substantially air impermeable. The nonwovenwebs (Comparative examples 3–5) are air permeable and liquid impermeableunder general conditions. However, the nonwoven webs become liquidpermeable under impact and/or pressure conditions.

Example 9

In this example, the absorbent barrier structure has a three-layeredconstruction as described in Example 2 is combined with an outer covermaterial, which is a polypropylene SM nonwoven web having a 16 gsm SBlayer and a 11.5 gsm MB layer. The combination structure is testedaccording to the Test Methods described herein. The test results aresummarized in Table 3.

TABLE 3 AIR HYDROHEAD LIQUID IMPACT PERMEABILITY PRESSURE TRANSMISSIONEXAMPLE (Darcy/mm) (mBars) VALUE (gsm) 9 13 71.7 5.1 2 24 49.3 6.8

When compared to the absorbent barrier structure of Example 2, thecombined structure enhances the liquid impermeability and resistance towet-through under impact but decreases the air permeability. Overall,the combined structure also provides the desired balance of properties.

Example 10

In this example, the absorbent barrier structure of Example 2 iscombined with an outer cover material according to Example 9. Further,an apertured film is disposed between the second barrier layer ofExample 2 and the outer cover of Example 9. The apertured film is madeof polyethylene having 11.7% open area. The apertures arehexagonal-shaped openings. The apertured film used herein ismanufactured by BP Chemicals, Wassergurg, Germany under the tradedesignation (HEX-B Type. 45109). Apertured films manufactured byTredegar Film Products Corporation, Terre Haute, Ind., under thedesignation HEX-B, are equally suitable for use herein.

The overall structure, including the absorbent barrier structure, theapertured film and the outer cover, are tested according to the TestMethods described herein, and are compare with Example 9, which does notinclude the apertured film. The results are summarized in Table 4 below.

TABLE 4 LIQUID IMPACT AIR TRANS- PERME- HYDROHEAD MISSION MVTR ABILITYPRESSURE VALUE (g/m²/ EXAMPLE (Darcy/mm) (mBars) (gsm) 24 hrs)  9 1371.7 5.1 3972 10 13 66.2 2.5 3434 (±10)

The open structure of the apertured film has insubstantial effect on theconvective air permeability overall. The apertured film reduces theliquid impermeability of the overall structure, especially under impactcondition. The results show that the overall structure including theaddition of the apertured film, still achieves the desired balance ofproperties. More importantly, the apertured film reduces the diffusiveMVTR of the overall structure. Thus, the unique combination ofpermeabilities provides a structure that desirably exhibits reduceddampness or condensation on the outer surface of the structure.

Example 11

In this example, the absorbent layer is a cellulosic web (namely, atwo-ply BOUNTY® towel) which has been surface-treated with a hydrophobicagent on both sides. The surface treatment method is described in PCTpublication WO 00/14296 (D'Agostino et al.) (corresponding to U.S. Ser.No. 09/786,075), the disclosure of which is incorporated herein byreference. The hydrophobic agent used is a fluorocarbon, namely,perfluoromethylcyclohexane. The treated cellulosic web is disposedbetween two barrier layers to form a three-layered absorbent barrierstructure. Example 11 has substantially the same structure as Example 2except that the treated BOUNTY® is used in place of the untreatedBOUNTY® as the absorbent layer. Table 5 below shows the properties ofthis example in comparison to the example using the untreated web.

TABLE 5 AIR HYDROHEAD LIQUID IMPACT PERMEABILITY PRESSURE TRANSMISSIONEXAMPLE (Darcy/mm) (mBars) VALUE (gsm) 11 27 74.3 4.7  2 24 49.3 6.8

The results show that the hydrophobic treatment significantly enhancesthe liquid impermeability while maintaining the air permeability.

Example 12

In this example, example 12 and Comparative example 2 are testedaccording to Test Method G (Post-Compaction Air Permeability). Example12 has substantially the same construction as example 3, except thatboth the first and the second barrier layers are spunbond/spunbondpolypropylene nonwoven webs made of microdenier fibers with a basisweight of about 17 gsm (available from First Quality Fibers Nonwovens,Hazelton, Pa. under the designation GCAS 16002184). The results aresummarized below in Table 6.

TABLE 6 PRE-COMPACTION POST-COMPACTION AIR PERMEABILITY AIR PERMEABILITYEXAMPLE (Darcy/mm) (Darcy/mm) Comp. 2 109 ± 10 66 ± 16 12 115 ± 7  94 ±8 

As the test results show that compaction results in insubstantial changein air permeability of example 12 of the absorbent barrier structure ofthe present invention. In contrast, a material, such as Comparativeexample 2, suffers significant loss in air permeability, which isattributable to its structural changes under compaction and itsinability to recover its original structure.

While particular embodiments of the present invention have beenillustrated and described, it would be apparent to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

1. An absorbent article comprising: a. a topsheet; b. an outer cover; c.an absorbent core disposed between the topsheet and the outer cover; d.an absorbent barrier structure is disposed between the absorbent coreand the outer cover wherein the absorbent barrier structure has ahydrohead value of at least about 10 mBars: a convective airpermeability of at least about 10 Darcy/mm; and a liquid impacttransmission value of less than about 20 g/m² and wherein said absorbentbarrier structure is substantially free of a film; and wherein saidbarrier structure comprises: 1) a first barrier zone disposed adjacentto a garment-facing surface of the absorbent core and a reservoir zonedisposed between the barrier zone and the outer cover; 2) a secondbarrier zone disposed at least partially between the reservoir zone andthe outer cover 3) a dampness management means disposed between theabsorbent barrier structure and the outer cover, or between thereservoir zone and one of the barrier zones wherein a combination of theabsorbent barrier structure and the outer cover has a hydrohead value ofat least about 25 mBars: a convective air permeability of at least about10 Darcy/mm; and a liquid impact transmission value of less than about20 g/m².
 2. The absorbent structure of claim 1 wherein the absorbentbarrier structure, the dampness management means and the outer covertogether has a MVTR of no more than 4500 g/m²/24 hrs.
 3. The absorbentstructure of claim 1 wherein the dampness management means is anapertured film having no more than about 20% open surface area.
 4. Anabsorbent article comprising: a. a topsheet; b. an outer cover that is anonwoven web or apertured film; c. an absorbent core disposed betweenthe topsheet and the outer cover; and d. an absorbent barrier structurethat is substantially free of a film is disposed between the absorbentcore and the outer cover and comprising: 1) a first fibrous barrier zonethat is a nonwoven web and is disposed adjacent to a garment-facingsurface of the absorbent core; 2) a reservoir zone that is a cellulosicweb and is disposed between the first fibrous barrier zone and the outercover; 3) a second fibrous barrier zone disposed between the reservoirzone and the outer cover; and wherein the barrier structure has aconvective air permeability of greater than about 10 Darcy/mm; a liquidimpact transmission value of less than about 20 g/m²; and apost-compression air permeability decrease of no more than about 35%;and wherein the combination of the absorbent barrier structure and theouter cover has a hydrohead value of at least about 10 mBars; aconvective air permeability of at least about 10 Darcy/mm; and a liquidimpact transmission value of less than about
 20. 5. The absorbentarticle of claim 4 further comprising a dampness management meansdisposed between the barrier structure and the outer cover or betweenthe reservoir zone and one of the barrier zones.
 6. The absorbentarticle of claim 5 wherein the dampness management means is an aperturedfilm having less than about 20% open surface area.